[PATCH 6/6] drm/tinydrm: Support device unplug
Noralf Trønnes
noralf at tronnes.org
Mon Aug 28 17:17:48 UTC 2017
Support device unplugging to make tinydrm suitable for USB devices.
Cc: David Lechner <david at lechnology.com>
Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
---
drivers/gpu/drm/tinydrm/core/tinydrm-core.c | 69 ++++++++++++++++++++++++-----
drivers/gpu/drm/tinydrm/mi0283qt.c | 4 ++
drivers/gpu/drm/tinydrm/mipi-dbi.c | 5 ++-
drivers/gpu/drm/tinydrm/repaper.c | 9 +++-
drivers/gpu/drm/tinydrm/st7586.c | 9 +++-
include/drm/tinydrm/tinydrm.h | 5 +++
6 files changed, 87 insertions(+), 14 deletions(-)
diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-core.c b/drivers/gpu/drm/tinydrm/core/tinydrm-core.c
index f11f4cd..3ccbcc5 100644
--- a/drivers/gpu/drm/tinydrm/core/tinydrm-core.c
+++ b/drivers/gpu/drm/tinydrm/core/tinydrm-core.c
@@ -32,6 +32,29 @@
* The driver allocates &tinydrm_device, initializes it using
* devm_tinydrm_init(), sets up the pipeline using tinydrm_display_pipe_init()
* and registers the DRM device using devm_tinydrm_register().
+ *
+ * Device unplug
+ * -------------
+ *
+ * tinydrm supports device unplugging when there's still open DRM or fbdev file
+ * handles.
+ *
+ * There are 2 ways for driver-device unbinding to happen:
+ *
+ * - The driver module is unloaded causing the driver to be unregistered.
+ * This can't happen as long as there's open file handles because a reference
+ * is taken on the module.
+ *
+ * - The device is removed (USB, Device Tree overlay).
+ * This can happen at any time.
+ *
+ * The driver needs to protect device resources from access after the device is
+ * gone. This is done checking drm_dev_is_unplugged(), typically in
+ * &drm_framebuffer_funcs.dirty, &drm_simple_display_pipe_funcs.enable and
+ * \.disable. Resources that doesn't face userspace and is only used with the
+ * device can be setup using devm\_ functions, but &tinydrm_device must be
+ * allocated using plain kzalloc() since it's lifetime can exceed that of the
+ * device. tinydrm_release() will free the structure.
*/
/**
@@ -138,6 +161,29 @@ static const struct drm_mode_config_funcs tinydrm_mode_config_funcs = {
.atomic_commit = drm_atomic_helper_commit,
};
+/**
+ * tinydrm_release - DRM driver release helper
+ * @drm: DRM device
+ *
+ * This function cleans up and finalizes &drm_device and frees &tinydrm_device.
+ *
+ * Drivers must use this as their &drm_driver->release callback.
+ */
+void tinydrm_release(struct drm_device *drm)
+{
+ struct tinydrm_device *tdev = drm_to_tinydrm(drm);
+
+ DRM_DEBUG_DRIVER("\n");
+
+ drm_mode_config_cleanup(drm);
+ drm_dev_fini(drm);
+
+ mutex_destroy(&tdev->dirty_lock);
+ kfree(tdev->fbdev_cma);
+ kfree(tdev);
+}
+EXPORT_SYMBOL(tinydrm_release);
+
static int tinydrm_init(struct device *parent, struct tinydrm_device *tdev,
const struct drm_framebuffer_funcs *fb_funcs,
struct drm_driver *driver)
@@ -160,8 +206,6 @@ static int tinydrm_init(struct device *parent, struct tinydrm_device *tdev,
static void tinydrm_fini(struct tinydrm_device *tdev)
{
- drm_mode_config_cleanup(&tdev->drm);
- mutex_destroy(&tdev->dirty_lock);
drm_dev_unref(&tdev->drm);
}
@@ -178,8 +222,8 @@ static void devm_tinydrm_release(void *data)
* @driver: DRM driver
*
* This function initializes @tdev, the underlying DRM device and it's
- * mode_config. Resources will be automatically freed on driver detach (devres)
- * using drm_mode_config_cleanup() and drm_dev_unref().
+ * mode_config. drm_dev_unref() is called on driver detach (devres) and when
+ * all refs are dropped, tinydrm_release() is called.
*
* Returns:
* Zero on success, negative error code on failure.
@@ -226,14 +270,17 @@ static int tinydrm_register(struct tinydrm_device *tdev)
static void tinydrm_unregister(struct tinydrm_device *tdev)
{
- struct drm_fbdev_cma *fbdev_cma = tdev->fbdev_cma;
-
drm_atomic_helper_shutdown(&tdev->drm);
- /* don't restore fbdev in lastclose, keep pipeline disabled */
- tdev->fbdev_cma = NULL;
- drm_dev_unregister(&tdev->drm);
- if (fbdev_cma)
- drm_fbdev_cma_fini(fbdev_cma);
+
+ /* Get a ref that will be put in tinydrm_fini() */
+ drm_dev_ref(&tdev->drm);
+
+ drm_fbdev_cma_dev_unplug(tdev->fbdev_cma);
+ drm_dev_unplug(&tdev->drm);
+
+ /* Make sure framebuffer flushing is done */
+ mutex_lock(&tdev->dirty_lock);
+ mutex_unlock(&tdev->dirty_lock);
}
static void devm_tinydrm_register_release(void *data)
diff --git a/drivers/gpu/drm/tinydrm/mi0283qt.c b/drivers/gpu/drm/tinydrm/mi0283qt.c
index 2465489..84ab8d1 100644
--- a/drivers/gpu/drm/tinydrm/mi0283qt.c
+++ b/drivers/gpu/drm/tinydrm/mi0283qt.c
@@ -31,6 +31,9 @@ static void mi0283qt_enable(struct drm_simple_display_pipe *pipe,
DRM_DEBUG_KMS("\n");
+ if (drm_dev_is_unplugged(&tdev->drm))
+ return;
+
ret = regulator_enable(mipi->regulator);
if (ret) {
dev_err(dev, "Failed to enable regulator (%d)\n", ret);
@@ -133,6 +136,7 @@ static struct drm_driver mi0283qt_driver = {
DRIVER_ATOMIC,
.fops = &mi0283qt_fops,
TINYDRM_GEM_DRIVER_OPS,
+ .release = tinydrm_release,
.lastclose = tinydrm_lastclose,
.debugfs_init = mipi_dbi_debugfs_init,
.name = "mi0283qt",
diff --git a/drivers/gpu/drm/tinydrm/mipi-dbi.c b/drivers/gpu/drm/tinydrm/mipi-dbi.c
index f5b9b772..49d03ab 100644
--- a/drivers/gpu/drm/tinydrm/mipi-dbi.c
+++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
@@ -209,7 +209,7 @@ static int mipi_dbi_fb_dirty(struct drm_framebuffer *fb,
mutex_lock(&tdev->dirty_lock);
- if (!mipi->enabled)
+ if (!mipi->enabled || drm_dev_is_unplugged(fb->dev))
goto out_unlock;
/* fbdev can flush even when we're not interested */
@@ -314,6 +314,9 @@ void mipi_dbi_pipe_disable(struct drm_simple_display_pipe *pipe)
DRM_DEBUG_KMS("\n");
+ if (drm_dev_is_unplugged(&tdev->drm))
+ return;
+
mipi->enabled = false;
if (mipi->backlight)
diff --git a/drivers/gpu/drm/tinydrm/repaper.c b/drivers/gpu/drm/tinydrm/repaper.c
index b8fc8eb..3869d362 100644
--- a/drivers/gpu/drm/tinydrm/repaper.c
+++ b/drivers/gpu/drm/tinydrm/repaper.c
@@ -542,7 +542,7 @@ static int repaper_fb_dirty(struct drm_framebuffer *fb,
mutex_lock(&tdev->dirty_lock);
- if (!epd->enabled)
+ if (!epd->enabled || drm_dev_is_unplugged(fb->dev))
goto out_unlock;
/* fbdev can flush even when we're not interested */
@@ -670,6 +670,9 @@ static void repaper_pipe_enable(struct drm_simple_display_pipe *pipe,
DRM_DEBUG_DRIVER("\n");
+ if (drm_dev_is_unplugged(&tdev->drm))
+ return;
+
/* Power up sequence */
gpiod_set_value_cansleep(epd->reset, 0);
gpiod_set_value_cansleep(epd->panel_on, 0);
@@ -803,6 +806,9 @@ static void repaper_pipe_disable(struct drm_simple_display_pipe *pipe)
DRM_DEBUG_DRIVER("\n");
+ if (drm_dev_is_unplugged(&tdev->drm))
+ return;
+
mutex_lock(&tdev->dirty_lock);
epd->enabled = false;
mutex_unlock(&tdev->dirty_lock);
@@ -894,6 +900,7 @@ static struct drm_driver repaper_driver = {
DRIVER_ATOMIC,
.fops = &repaper_fops,
TINYDRM_GEM_DRIVER_OPS,
+ .release = tinydrm_release,
.name = "repaper",
.desc = "Pervasive Displays RePaper e-ink panels",
.date = "20170405",
diff --git a/drivers/gpu/drm/tinydrm/st7586.c b/drivers/gpu/drm/tinydrm/st7586.c
index bc2b905..b1bfc4e 100644
--- a/drivers/gpu/drm/tinydrm/st7586.c
+++ b/drivers/gpu/drm/tinydrm/st7586.c
@@ -120,7 +120,7 @@ static int st7586_fb_dirty(struct drm_framebuffer *fb,
mutex_lock(&tdev->dirty_lock);
- if (!mipi->enabled)
+ if (!mipi->enabled || drm_dev_is_unplugged(fb->dev))
goto out_unlock;
/* fbdev can flush even when we're not interested */
@@ -184,6 +184,9 @@ static void st7586_pipe_enable(struct drm_simple_display_pipe *pipe,
DRM_DEBUG_KMS("\n");
+ if (drm_dev_is_unplugged(&tdev->drm))
+ return;
+
mipi_dbi_hw_reset(mipi);
ret = mipi_dbi_command(mipi, ST7586_AUTO_READ_CTRL, 0x9f);
if (ret) {
@@ -252,6 +255,9 @@ static void st7586_pipe_disable(struct drm_simple_display_pipe *pipe)
DRM_DEBUG_KMS("\n");
+ if (drm_dev_is_unplugged(&tdev->drm))
+ return;
+
if (!mipi->enabled)
return;
@@ -319,6 +325,7 @@ static struct drm_driver st7586_driver = {
DRIVER_ATOMIC,
.fops = &st7586_fops,
TINYDRM_GEM_DRIVER_OPS,
+ .release = tinydrm_release,
.lastclose = tinydrm_lastclose,
.debugfs_init = mipi_dbi_debugfs_init,
.name = "st7586",
diff --git a/include/drm/tinydrm/tinydrm.h b/include/drm/tinydrm/tinydrm.h
index ded9817..4265f51 100644
--- a/include/drm/tinydrm/tinydrm.h
+++ b/include/drm/tinydrm/tinydrm.h
@@ -23,6 +23,10 @@
* @fbdev_cma: CMA fbdev structure
* @suspend_state: Atomic state when suspended
* @fb_funcs: Framebuffer functions used when creating framebuffers
+ *
+ * Drivers that embed &tinydrm_device must set it as the first member because
+ * it is freed in tinydrm_release(). This means that the structure must be
+ * allocated with kzalloc() and not the devm\_ version.
*/
struct tinydrm_device {
struct drm_device drm;
@@ -94,6 +98,7 @@ struct drm_gem_object *
tinydrm_gem_cma_prime_import_sg_table(struct drm_device *drm,
struct dma_buf_attachment *attach,
struct sg_table *sgt);
+void tinydrm_release(struct drm_device *drm);
int devm_tinydrm_init(struct device *parent, struct tinydrm_device *tdev,
const struct drm_framebuffer_funcs *fb_funcs,
struct drm_driver *driver);
--
2.7.4
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