[PATCH v5 4/7] video: add generic framebuffer eviction

[Noralf Trønnes]

Den 05.09.2016 13:19, skrev David Herrmann:
> Hi
>
> On Sat, Sep 3, 2016 at 2:06 PM, Noralf Trønnes <noralf at tronnes.org> wrote:
>> Den 02.09.2016 10:22, skrev David Herrmann:
>>> There are several situations where we want hardware handover from an early
>>> boot GFX driver (e.g., vgacon, vesafb, efifb, simplefb) to a full fletched
>>> GFX driver (e.g., most DRM drivers). So far, we relied on
>>> remove_conflicting_framebuffers() to do this for us, however, this had a
>>> bunch of downsides:
>>>
>>>     o It only removes conflicting fbdev drivers. It does not drop vgacon,
>>>       early boot console drivers, conflicting DRM drivers, etc.
>>>
>>>     o It only unloads the fbdev driver, it does not modify the underlying
>>>       device or resources. In case of "screen_info" drivers (e.g., efifb)
>>>       this is fine, since no resources are pinned. However, if the driver
>>>       binds to a platform-device like "simple-framebuffer", we must make
>>>       sure to unregister that device as well. Otherwise, pinned resources
>>>       like IORESOURCE_MEM stay around, triggering WARN_ONs if the following
>>>       driver requests those resources.
>>>
>>>     o It is only available if CONFIG_FB is selected.
>>>
>>> This commit adds a new infrastructure that manages system-framebuffers
>>> (short: sysfb). The initial commit provides conflict-resolution for
>>> system-framebuffers. At its core it provides sysfb_evict_conflicts(),
>>> which implements conflict detection and removal for all known types of
>>> GFX driver hand-overs. So far, this includes platform-device removal,
>>> fbdev-firmware-device removal, vgacon removal and VBE detection. To
>>> further simplify the callers, it also provides helpers to figure out what
>>> hand-over to do, based on the device the new drivers binds to:
>>>
>>>     o PCI drivers can use sysfb_evict_conflicts_pci(), which will figure
>>> out
>>>       the apertures automatically, and does VGA/VBE detection.
>>>
>>>     o Generic firmware drivers that might be shadowed at any address in
>>>       memory can use sysfb_evict_conflicts_firmware(), basically removing
>>>       *all* firmware framebuffers in effect.
>>>
>>> This only adds the generic sysfb helpers. No users are converted, yet.
>>>
>>> Signed-off-by: David Herrmann <dh.herrmann at gmail.com>
>>> ---
>>>    drivers/video/Kconfig  |   4 +
>>>    drivers/video/Makefile |   1 +
>>>    drivers/video/sysfb.c  | 327
>>> +++++++++++++++++++++++++++++++++++++++++++++++++
>>>    include/linux/sysfb.h  |  34 +++++
>>>    4 files changed, 366 insertions(+)
>>>    create mode 100644 drivers/video/sysfb.c
>>>    create mode 100644 include/linux/sysfb.h
>>>
>>> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
>>> index 3c20af9..56a8294 100644
>>> --- a/drivers/video/Kconfig
>>> +++ b/drivers/video/Kconfig
>>> @@ -36,6 +36,10 @@ config VIDEOMODE_HELPERS
>>>    config HDMI
>>>          bool
>>>    +config SYSFB
>>> +       bool
>>> +       select DUMMY_CONSOLE if VT
>>> +
>>>    if VT
>>>          source "drivers/video/console/Kconfig"
>>>    endif
>>> diff --git a/drivers/video/Makefile b/drivers/video/Makefile
>>> index 9ad3c17..df7bd75 100644
>>> --- a/drivers/video/Makefile
>>> +++ b/drivers/video/Makefile
>>> @@ -1,5 +1,6 @@
>>>    obj-$(CONFIG_VGASTATE)            += vgastate.o
>>>    obj-$(CONFIG_HDMI)                += hdmi.o
>>> +obj-$(CONFIG_SYSFB)              += sysfb.o
>>>      obj-$(CONFIG_VT)              += console/
>>>    obj-$(CONFIG_LOGO)              += logo/
>>> diff --git a/drivers/video/sysfb.c b/drivers/video/sysfb.c
>>> new file mode 100644
>>> index 0000000..00585c9
>>> --- /dev/null
>>> +++ b/drivers/video/sysfb.c
>>> @@ -0,0 +1,327 @@
>>> +/*
>>> + * Copyright (C) 2013-2016 Red Hat, Inc.
>>> + *
>>> + * This program is free software; you can redistribute it and/or modify
>>> it
>>> + * under the terms of the GNU Lesser General Public License as published
>>> by the
>>> + * Free Software Foundation; either version 2.1 of the License, or (at
>>> your
>>> + * option) any later version.
>>> + */
>>> +
>>> +#define pr_fmt(fmt) "sysfb: " fmt
>>> +#include <linux/console.h>
>>> +#include <linux/device.h>
>>> +#include <linux/err.h>
>>> +#include <linux/export.h>
>>> +#include <linux/fb.h>
>>> +#include <linux/ioport.h>
>>> +#include <linux/kernel.h>
>>> +#include <linux/of.h>
>>> +#include <linux/of_platform.h>
>>> +#include <linux/pci.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/sysfb.h>
>>> +#include <linux/vt.h>
>>> +
>>> +static bool sysfb_evict_match_resource(struct sysfb_evict_ctx *ctx,
>>> +                                      struct resource *mem)
>>> +{
>>> +       struct aperture *g;
>>> +       unsigned int i;
>>> +
>>> +       for (i = 0; i < ctx->ap->count; ++i) {
>>> +               g = &ctx->ap->ranges[i];
>>> +
>>> +               if (mem->start == g->base)
>>> +                       return true;
>>> +               if (mem->start >= g->base && mem->end < g->base + g->size)
>>> +                       return true;
>>> +               if ((ctx->flags & SYSFB_EVICT_VBE) && mem->start ==
>>> 0xA0000)
>>> +                       return true;
>>> +       }
>>> +
>>> +       return false;
>>> +}
>>> +
>>> +static int sysfb_evict_platform_device(struct device *dev, void
>>> *userdata)
>>> +{
>>> +       struct sysfb_evict_ctx *ctx = userdata;
>>> +       struct platform_device *pdev = to_platform_device(dev);
>>> +       struct resource *mem;
>>> +
>>> +       if (!pdev->name)
>>> +               return 0;
>>> +
>>> +       if (!strcmp(pdev->name, "simple-framebuffer")) {
>>
>> This doesn't work in my case where the device comes from DT and the name
>> also contains the address: pdev->name=1e887000.framebuffer
>>
>> This is one way of solving it:
>>
>>         if (!pdev->dev.driver || !pdev->dev.driver->name)
>>                  return 0;
>>
>>         if (!strcmp(pdev->dev.driver->name, "simple-framebuffer")) {
> Thanks for the hint, but this would skip devices that are not bound.
> How about the attached hunk?
>
> Thanks
> David
>
> diff --git a/drivers/video/sysfb.c b/drivers/video/sysfb.c
> index 0f039c6..a4ace3f 100644
> --- a/drivers/video/sysfb.c
> +++ b/drivers/video/sysfb.c
> @@ -50,10 +50,8 @@ static int sysfb_evict_platform_device
>          struct platform_device *pdev = to_platform_device(dev);
>          struct resource *mem;
>
> -       if (!pdev->name)
> -               return 0;
> -
> -       if (!strcmp(pdev->name, "simple-framebuffer")) {
> +       if ((pdev->name && !strcmp(pdev->name, "simple-framebuffer")) ||
> +           of_device_is_compatible(pdev->dev.of_node, "simple-framebuffer")) {
>                  mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>                  if (!mem)
>                          return 0;
>

This worked fine.

Noralf.