[PATCH v2] drm/tinydrm: Move backlight helpers to a separate file
Meghana Madhyastha
meghana.madhyastha at gmail.com
Tue Sep 26 12:49:18 UTC 2017
On Tue, Sep 26, 2017 at 01:32:15PM +0200, Daniel Vetter wrote:
> On Tue, Sep 26, 2017 at 04:46:53PM +0530, Meghana Madhyastha wrote:
> > On Mon, Sep 25, 2017 at 06:31:58PM +0200, Noralf Trønnes wrote:
> > >
> > > Den 25.09.2017 16.56, skrev Noralf Trønnes:
> > > >Hi Meghana,
> > > >
> > > >
> > > >Den 22.09.2017 17.09, skrev Meghana Madhyastha:
> > > >>Move backlight helpers from tinydrm-helpers.c to
> > > >>tinydrm-backlight.c. This is because it is organizationally
> > > >>simpler to understand and advantageous to group functions
> > > >>performing a similar function to a separate file as opposed to
> > > >>having one helper file with heteregenous helper functions.
> > > >>
> > > >>Signed-off-by: Meghana Madhyastha <meghana.madhyastha at gmail.com>
> > > >>---
> > > >
> > > >I don't think there is much gain in just moving the code like this.
> > > >
> > > >The idea is to add a drm_backlight helper that can be useful for all
> > > >DRM drivers that use the backlight subsystem.
> >
> > Yes I agree. That definitely makes more sense.
> > >
> > > The full path to that helper would be:
> > > drivers/gpu/drm/drm_backlight.c
> > >
> > > >This is what the TODO says:
> > > >https://dri.freedesktop.org/docs/drm/gpu/todo.html#tinydrm
> > > >
> > > >- backlight helpers, probably best to put them into a new drm_backlight.c.
> > > > This is because drivers/video is de-facto unmaintained. We could also
> > > > move drivers/video/backlight to drivers/gpu/backlight and take it all
> > > > over within drm-misc, but that’s more work.
> > > >
> > > >There is also this discussion to take into account:
> > > >KMS backlight ABI proposition
> > > >https://lists.freedesktop.org/archives/dri-devel/2017-February/133206.html
> > > >
> > > >
> > > >I don't remember what came out of that discussion.
> > > >
> > > >Noralf.
> >
> > After having discussed this with Daniel on the #dri-devel irc channel,
> > here are some of the points suggested.
> >
> > Daniel suggested that I first look into the usage of shared backlight
> > helpers in drm (specifically backlight_update_status to begin with). The idea
> > was to see whether there is any pattern in usage and/or code dupication.
> > If there is, then the next step would be to write helper functions which
> > can be used by other drivers (and not just tinydrm).
> >
> > To start with, I went through the instances of backlight_update_status
> > in the drm code, and made the following observations(most of them are
> > very simple/naive observations).
> >
> > - backlight_update_status is usually called in backlight init (and
> > sometimes exit) functions of the drivers just after the device is registered.
> > So backlight_update_status is called with the registered device as the
> > parameter.
> >
> > Here are the following cases of properties changed/set before
> > backlight_update_status is called.
> >
> > - CASE 1: Brightness is changed (either a macro BRIGHTNESS_MAX_LEVEL 100
> > is defined or it is manually set) This happens in the following files:
> >
> > gma500/cdv_device.c, gma500/mdfld_device.c, gma500/oaktrail_device.c,
> > gma500/psb_device.c, noveau/noveau_backlight.c(here brightness is determined by fuction
> > static int nv50_get_intensity)
> >
> > - CASE 2: Power property is set (to FB_BLANK_UNBLANK mostly)
> > This happens in the following files:
> >
> > omapdrm/displays/panel-dpi.c, panel/panel-innolux-p079zca.c,
> > panel/panel-jdi-lt070me05000.c, panel/panel-sharp-lq101r1sx01.c,
> > panel/panel-sharp-ls043t1le01.c, tilcdc/tilcdc_panel.c
> >
> > - CASE 3: State is set
> > This happens in the following files:
> >
> > tinydrm/tinydrm-helpers.c
> >
> > - CASE 4: Power and brightness properties are set
> > This happens in the following files:
> >
> > atombios_encoders.c, radeon/radeon_legacy_encoders.c,
> > shmobile/shmob_drm_backlight.c
> >
> > - CASE 5: Power and the state properties are set
> > This happens in the following files:
> >
> > panel/panel-lvds.c, panel/panel-panasonic-vvx10f034n00.c,
> > panel/panel-simple.c, panel/panel-sitronix-st7789v.c
> >
> > Please let me know if I am wrong / missed something. As for next steps,
> > wouldn't it be an overkill to have a separate helper function for each
> > of these cases ? Perhaps a generic helper function which would somehow
> > address these cases would be more appropriate ? Thank you for your
> > time/patience.
>
> I suspect that a lot of these combinations are just plain wrong, but
> happen to kinda work with the combination of gpu driver and backlight
> driver they're used on. tbh I have no idea which one is the correct
> version for enabling a backlight correctly ...
So does this mean that different devices require different combinations
in order to enable a backlight ? Is it wrong or is it just that it
depends on the gpu driver ?
> So definitely a good task to refactor this into a proper helper, but looks
> a lot more involved than at first sight.
Yes it does look more involved than it did initially. Would a good
starting point be then to try to find out if there is one common
combination that can be used to enable any backlight device of any gpu
driver ?
> Do you have any of the hardware supported by any of these drivers? lsmod
> and then comparing with the modules you're building in your own tree
> should help you figure this out.
> -Daniel
I don't have all of the hardware. However, some of the modules such as
radeon, amdgpu and gma500 drivers were successfully loaded so my system
supports some of the hardware.
-Meghana
> >
> > -Meghana
> >
> > > >>Changes in v2:
> > > >> -Improved commit message by explaining why the changes were made.
> > > >>
> > > >> drivers/gpu/drm/tinydrm/core/Makefile | 2 +-
> > > >> drivers/gpu/drm/tinydrm/core/tinydrm-backlight.c | 103
> > > >>+++++++++++++++++++++++
> > > >> drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 94
> > > >>---------------------
> > > >> drivers/gpu/drm/tinydrm/mi0283qt.c | 1 +
> > > >> drivers/gpu/drm/tinydrm/mipi-dbi.c | 1 +
> > > >> include/drm/tinydrm/tinydrm-backlight.h | 18 ++++
> > > >> 6 files changed, 124 insertions(+), 95 deletions(-)
> > > >> create mode 100644 drivers/gpu/drm/tinydrm/core/tinydrm-backlight.c
> > > >> create mode 100644 include/drm/tinydrm/tinydrm-backlight.h
> > > >>
> > > >>diff --git a/drivers/gpu/drm/tinydrm/core/Makefile
> > > >>b/drivers/gpu/drm/tinydrm/core/Makefile
> > > >>index fb221e6..389ca7a 100644
> > > >>--- a/drivers/gpu/drm/tinydrm/core/Makefile
> > > >>+++ b/drivers/gpu/drm/tinydrm/core/Makefile
> > > >>@@ -1,3 +1,3 @@
> > > >>-tinydrm-y := tinydrm-core.o tinydrm-pipe.o tinydrm-helpers.o
> > > >>+tinydrm-y := tinydrm-core.o tinydrm-pipe.o tinydrm-backlight.o
> > > >>tinydrm-helpers.o
> > > >> obj-$(CONFIG_DRM_TINYDRM) += tinydrm.o
> > > >>diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-backlight.c
> > > >>b/drivers/gpu/drm/tinydrm/core/tinydrm-backlight.c
> > > >>new file mode 100644
> > > >>index 0000000..dc6f17d
> > > >>--- /dev/null
> > > >>+++ b/drivers/gpu/drm/tinydrm/core/tinydrm-backlight.c
> > > >>@@ -0,0 +1,103 @@
> > > >>+#include <linux/backlight.h>
> > > >>+#include <linux/dma-buf.h>
> > > >>+#include <linux/pm.h>
> > > >>+#include <linux/swab.h>
> > > >>+
> > > >>+#include <drm/tinydrm/tinydrm.h>
> > > >>+#include <drm/tinydrm/tinydrm-backlight.h>
> > > >>+
> > > >>+/**
> > > >>+ * tinydrm_of_find_backlight - Find backlight device in device-tree
> > > >>+ * @dev: Device
> > > >>+ *
> > > >>+ * This function looks for a DT node pointed to by a property named
> > > >>'backlight'
> > > >>+ * and uses of_find_backlight_by_node() to get the backlight device.
> > > >>+ * Additionally if the brightness property is zero, it is set to
> > > >>+ * max_brightness.
> > > >>+ *
> > > >>+ * Returns:
> > > >>+ * NULL if there's no backlight property.
> > > >>+ * Error pointer -EPROBE_DEFER if the DT node is found, but no
> > > >>backlight device
> > > >>+ * is found.
> > > >>+ * If the backlight device is found, a pointer to the structure is
> > > >>returned.
> > > >>+ */
> > > >>+
> > > >>+struct backlight_device *tinydrm_of_find_backlight(struct device *dev)
> > > >>+{
> > > >>+ struct backlight_device *backlight;
> > > >>+ struct device_node *np;
> > > >>+
> > > >>+ np = of_parse_phandle(dev->of_node, "backlight", 0);
> > > >>+ if (!np)
> > > >>+ return NULL;
> > > >>+
> > > >>+ backlight = of_find_backlight_by_node(np);
> > > >>+ of_node_put(np);
> > > >>+
> > > >>+ if (!backlight)
> > > >>+ return ERR_PTR(-EPROBE_DEFER);
> > > >>+
> > > >>+ if (!backlight->props.brightness) {
> > > >>+ backlight->props.brightness = backlight->props.max_brightness;
> > > >>+ DRM_DEBUG_KMS("Backlight brightness set to %d\n",
> > > >>+ backlight->props.brightness);
> > > >>+ }
> > > >>+
> > > >>+ return backlight;
> > > >>+}
> > > >>+EXPORT_SYMBOL(tinydrm_of_find_backlight);
> > > >>+
> > > >>+/**
> > > >>+ * tinydrm_enable_backlight - Enable backlight helper
> > > >>+ * @backlight: Backlight device
> > > >>+ *
> > > >>+ * Returns:
> > > >>+ * Zero on success, negative error code on failure.
> > > >>+ */
> > > >>+int tinydrm_enable_backlight(struct backlight_device *backlight)
> > > >>+{
> > > >>+ unsigned int old_state;
> > > >>+ int ret;
> > > >>+
> > > >>+ if (!backlight)
> > > >>+ return 0;
> > > >>+
> > > >>+ old_state = backlight->props.state;
> > > >>+ backlight->props.state &= ~BL_CORE_FBBLANK;
> > > >>+ DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
> > > >>+ backlight->props.state);
> > > >>+
> > > >>+ ret = backlight_update_status(backlight);
> > > >>+ if (ret)
> > > >>+ DRM_ERROR("Failed to enable backlight %d\n", ret);
> > > >>+
> > > >>+ return ret;
> > > >>+}
> > > >>+EXPORT_SYMBOL(tinydrm_enable_backlight);
> > > >>+
> > > >>+/**
> > > >>+ * tinydrm_disable_backlight - Disable backlight helper
> > > >>+ * @backlight: Backlight device
> > > >>+ *
> > > >>+ * Returns:
> > > >>+ * Zero on success, negative error code on failure.
> > > >>+ */
> > > >>+int tinydrm_disable_backlight(struct backlight_device *backlight)
> > > >>+{
> > > >>+ unsigned int old_state;
> > > >>+ int ret;
> > > >>+
> > > >>+ if (!backlight)
> > > >>+ return 0;
> > > >>+
> > > >>+ old_state = backlight->props.state;
> > > >>+ backlight->props.state |= BL_CORE_FBBLANK;
> > > >>+ DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
> > > >>+ backlight->props.state);
> > > >>+ ret = backlight_update_status(backlight);
> > > >>+ if (ret)
> > > >>+ DRM_ERROR("Failed to disable backlight %d\n", ret);
> > > >>+
> > > >>+ return ret;
> > > >>+}
> > > >>+EXPORT_SYMBOL(tinydrm_disable_backlight);
> > > >>diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> > > >>b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> > > >>index bd6cce0..ee8ad8c 100644
> > > >>--- a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> > > >>+++ b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> > > >>@@ -236,100 +236,6 @@ void tinydrm_xrgb8888_to_gray8(u8 *dst, void
> > > >>*vaddr, struct drm_framebuffer *fb,
> > > >> }
> > > >> EXPORT_SYMBOL(tinydrm_xrgb8888_to_gray8);
> > > >> -/**
> > > >>- * tinydrm_of_find_backlight - Find backlight device in device-tree
> > > >>- * @dev: Device
> > > >>- *
> > > >>- * This function looks for a DT node pointed to by a property named
> > > >>'backlight'
> > > >>- * and uses of_find_backlight_by_node() to get the backlight device.
> > > >>- * Additionally if the brightness property is zero, it is set to
> > > >>- * max_brightness.
> > > >>- *
> > > >>- * Returns:
> > > >>- * NULL if there's no backlight property.
> > > >>- * Error pointer -EPROBE_DEFER if the DT node is found, but no
> > > >>backlight device
> > > >>- * is found.
> > > >>- * If the backlight device is found, a pointer to the structure is
> > > >>returned.
> > > >>- */
> > > >>-struct backlight_device *tinydrm_of_find_backlight(struct device *dev)
> > > >>-{
> > > >>- struct backlight_device *backlight;
> > > >>- struct device_node *np;
> > > >>-
> > > >>- np = of_parse_phandle(dev->of_node, "backlight", 0);
> > > >>- if (!np)
> > > >>- return NULL;
> > > >>-
> > > >>- backlight = of_find_backlight_by_node(np);
> > > >>- of_node_put(np);
> > > >>-
> > > >>- if (!backlight)
> > > >>- return ERR_PTR(-EPROBE_DEFER);
> > > >>-
> > > >>- if (!backlight->props.brightness) {
> > > >>- backlight->props.brightness = backlight->props.max_brightness;
> > > >>- DRM_DEBUG_KMS("Backlight brightness set to %d\n",
> > > >>- backlight->props.brightness);
> > > >>- }
> > > >>-
> > > >>- return backlight;
> > > >>-}
> > > >>-EXPORT_SYMBOL(tinydrm_of_find_backlight);
> > > >>-
> > > >>-/**
> > > >>- * tinydrm_enable_backlight - Enable backlight helper
> > > >>- * @backlight: Backlight device
> > > >>- *
> > > >>- * Returns:
> > > >>- * Zero on success, negative error code on failure.
> > > >>- */
> > > >>-int tinydrm_enable_backlight(struct backlight_device *backlight)
> > > >>-{
> > > >>- unsigned int old_state;
> > > >>- int ret;
> > > >>-
> > > >>- if (!backlight)
> > > >>- return 0;
> > > >>-
> > > >>- old_state = backlight->props.state;
> > > >>- backlight->props.state &= ~BL_CORE_FBBLANK;
> > > >>- DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
> > > >>- backlight->props.state);
> > > >>-
> > > >>- ret = backlight_update_status(backlight);
> > > >>- if (ret)
> > > >>- DRM_ERROR("Failed to enable backlight %d\n", ret);
> > > >>-
> > > >>- return ret;
> > > >>-}
> > > >>-EXPORT_SYMBOL(tinydrm_enable_backlight);
> > > >>-
> > > >>-/**
> > > >>- * tinydrm_disable_backlight - Disable backlight helper
> > > >>- * @backlight: Backlight device
> > > >>- *
> > > >>- * Returns:
> > > >>- * Zero on success, negative error code on failure.
> > > >>- */
> > > >>-int tinydrm_disable_backlight(struct backlight_device *backlight)
> > > >>-{
> > > >>- unsigned int old_state;
> > > >>- int ret;
> > > >>-
> > > >>- if (!backlight)
> > > >>- return 0;
> > > >>-
> > > >>- old_state = backlight->props.state;
> > > >>- backlight->props.state |= BL_CORE_FBBLANK;
> > > >>- DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
> > > >>- backlight->props.state);
> > > >>- ret = backlight_update_status(backlight);
> > > >>- if (ret)
> > > >>- DRM_ERROR("Failed to disable backlight %d\n", ret);
> > > >>-
> > > >>- return ret;
> > > >>-}
> > > >>-EXPORT_SYMBOL(tinydrm_disable_backlight);
> > > >> #if IS_ENABLED(CONFIG_SPI)
> > > >> diff --git a/drivers/gpu/drm/tinydrm/mi0283qt.c
> > > >>b/drivers/gpu/drm/tinydrm/mi0283qt.c
> > > >>index 7e5bb7d..c161d45 100644
> > > >>--- a/drivers/gpu/drm/tinydrm/mi0283qt.c
> > > >>+++ b/drivers/gpu/drm/tinydrm/mi0283qt.c
> > > >>@@ -12,6 +12,7 @@
> > > >> #include <drm/tinydrm/ili9341.h>
> > > >> #include <drm/tinydrm/mipi-dbi.h>
> > > >> #include <drm/tinydrm/tinydrm-helpers.h>
> > > >>+#include <drm/tinydrm/tinydrm-backlight.h>
> > > >> #include <linux/delay.h>
> > > >> #include <linux/gpio/consumer.h>
> > > >> #include <linux/module.h>
> > > >>diff --git a/drivers/gpu/drm/tinydrm/mipi-dbi.c
> > > >>b/drivers/gpu/drm/tinydrm/mipi-dbi.c
> > > >>index 2caeabc..dc84f26 100644
> > > >>--- a/drivers/gpu/drm/tinydrm/mipi-dbi.c
> > > >>+++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
> > > >>@@ -11,6 +11,7 @@
> > > >> #include <drm/tinydrm/mipi-dbi.h>
> > > >> #include <drm/tinydrm/tinydrm-helpers.h>
> > > >>+#include <drm/tinydrm/tinydrm-backlight.h>
> > > >> #include <linux/debugfs.h>
> > > >> #include <linux/dma-buf.h>
> > > >> #include <linux/gpio/consumer.h>
> > > >>diff --git a/include/drm/tinydrm/tinydrm-backlight.h
> > > >>b/include/drm/tinydrm/tinydrm-backlight.h
> > > >>new file mode 100644
> > > >>index 0000000..6a7b6d5
> > > >>--- /dev/null
> > > >>+++ b/include/drm/tinydrm/tinydrm-backlight.h
> > > >>@@ -0,0 +1,18 @@
> > > >>+/*
> > > >>+ * Copyright (C) 2016 Noralf Trønnes
> > > >>+ *
> > > >>+ * This program is free software; you can redistribute it and/or modify
> > > >>+ * it under the terms of the GNU General Public License as published by
> > > >>+ * the Free Software Foundation; either version 2 of the License, or
> > > >>+ * (at your option) any later version.
> > > >>+ */
> > > >>+
> > > >>+#ifndef __LINUX_TINYDRM_BACKLIGHT_H
> > > >>+#define __LINUX_TINYDRM_BACKLIGHT_H
> > > >>+
> > > >>+struct backlight_device;
> > > >>+struct backlight_device *tinydrm_of_find_backlight(struct device *dev);
> > > >>+int tinydrm_enable_backlight(struct backlight_device *backlight);
> > > >>+int tinydrm_disable_backlight(struct backlight_device *backlight);
> > > >>+
> > > >>+#endif /* __LINUX_TINYDRM_BACKLIGHT_H */
> > > >
> > > >_______________________________________________
> > > >dri-devel mailing list
> > > >dri-devel at lists.freedesktop.org
> > > >https://lists.freedesktop.org/mailman/listinfo/dri-devel
> > > >
> > >
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
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