Re: [PATCH 4/6] drm/tinydrm: Embed drm_device in tinydrm_device

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Noralf,

On Thursday, 31 August 2017 20:16:42 EEST Noralf Trønnes wrote:
> Den 31.08.2017 12.18, skrev Laurent Pinchart:
> > On Monday, 28 August 2017 20:17:46 EEST Noralf Trønnes wrote:
> >> Might as well embed drm_device since tinydrm_device (embeds pipe struct
> >> and fbdev pointer) needs to stick around after driver-device unbind to
> >> handle open fd's after device removal.
> >> 
> >> Cc: David Lechner <david@lechnology.com>
> >> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> >> ---
> >> 
> >>   drivers/gpu/drm/tinydrm/core/tinydrm-core.c | 44 +++++++++++-----------
> >>   drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c |  2 +-
> >>   drivers/gpu/drm/tinydrm/mi0283qt.c          |  8 +++---
> >>   drivers/gpu/drm/tinydrm/mipi-dbi.c          | 12 ++++----
> >>   drivers/gpu/drm/tinydrm/repaper.c           | 10 +++----
> >>   drivers/gpu/drm/tinydrm/st7586.c            | 16 +++++------
> >>   include/drm/tinydrm/tinydrm.h               |  9 +++++-
> >>   7 files changed, 50 insertions(+), 51 deletions(-)
> >> 
> >> diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-core.c
> >> b/drivers/gpu/drm/tinydrm/core/tinydrm-core.c index 551709e..f11f4cd
> >> 100644
> >> --- a/drivers/gpu/drm/tinydrm/core/tinydrm-core.c
> >> +++ b/drivers/gpu/drm/tinydrm/core/tinydrm-core.c
> > 
> > [snip]
> > 
> >> @@ -142,23 +142,16 @@ static int tinydrm_init(struct device *parent,
> >> struct
> >> tinydrm_device *tdev, const struct drm_framebuffer_funcs *fb_funcs,
> >> 
> >>   			struct drm_driver *driver)
> >>   
> >>   {
> >> 
> >> -	struct drm_device *drm;
> >> +	struct drm_device *drm = &tdev->drm;
> >> +	int ret;
> >> 
> >>   	mutex_init(&tdev->dirty_lock);
> >>   	tdev->fb_funcs = fb_funcs;
> >> 
> >> -	/*
> >> -	 * We don't embed drm_device, because that prevent us from using
> >> -	 * devm_kzalloc() to allocate tinydrm_device in the driver since
> >> -	 * drm_dev_unref() frees the structure. The devm_ functions provide
> >> -	 * for easy error handling.
> > 
> > Don't you then need a custom drm_driver.release handler to free the parent
> > structure ?
> 
> I rely on the fact that drm_device is the first member in the driver
> structure and thus it will be freed in drm_dev_release(). A later patch
> adds a drm_driver.release function though.

That's a bit hackish. As a later patch changes this I'd be OK with this one, 
but you should mention that you rely on the structure layout in the commit 
message.

> >> -	 */
> >> -	drm = drm_dev_alloc(driver, parent);
> >> -	if (IS_ERR(drm))
> >> -		return PTR_ERR(drm);
> >> -
> >> -	tdev->drm = drm;
> >> -	drm->dev_private = tdev;
> >> +	ret = drm_dev_init(drm, driver, parent);
> >> +	if (ret)
> >> +		return ret;
> >> +
> >> 
> >>   	drm_mode_config_init(drm);
> >>   	drm->mode_config.funcs = &tinydrm_mode_config_funcs;
> > 
> > [snip]
> > 
> >> diff --git a/drivers/gpu/drm/tinydrm/mi0283qt.c
> >> b/drivers/gpu/drm/tinydrm/mi0283qt.c index 7e5bb7d..77d40c9 100644
> >> --- a/drivers/gpu/drm/tinydrm/mi0283qt.c
> >> +++ b/drivers/gpu/drm/tinydrm/mi0283qt.c
> > 
> > [snip]
> > 
> >> @@ -169,7 +169,7 @@ static int mi0283qt_probe(struct spi_device *spi)
> >> 
> >>   	u32 rotation = 0;
> >>   	int ret;
> >> 
> >> -	mipi = devm_kzalloc(dev, sizeof(*mipi), GFP_KERNEL);
> >> +	mipi = kzalloc(sizeof(*mipi), GFP_KERNEL);
> > 
> > Where's the related kfree() ?
> > 
> >>   	if (!mipi)
> >>   	
> >>   		return -ENOMEM;
> > 
> > [snip]
> > 
> >> diff --git a/drivers/gpu/drm/tinydrm/repaper.c
> >> b/drivers/gpu/drm/tinydrm/repaper.c index 30dc97b..b8fc8eb 100644
> >> --- a/drivers/gpu/drm/tinydrm/repaper.c
> >> +++ b/drivers/gpu/drm/tinydrm/repaper.c
> > 
> > [snip]
> > 
> >> @@ -949,7 +949,7 @@ static int repaper_probe(struct spi_device *spi)
> >> 
> >>   		}
> >>   	
> >>   	}
> >> 
> >> -	epd = devm_kzalloc(dev, sizeof(*epd), GFP_KERNEL);
> >> +	epd = kzalloc(sizeof(*epd), GFP_KERNEL);
> > 
> > Ditto.
> > 
> >>   	if (!epd)
> >>   	
> >>   		return -ENOMEM;
> > 
> > [snip]
> > 
> >> diff --git a/drivers/gpu/drm/tinydrm/st7586.c
> >> b/drivers/gpu/drm/tinydrm/st7586.c index b439956..bc2b905 100644
> >> --- a/drivers/gpu/drm/tinydrm/st7586.c
> >> +++ b/drivers/gpu/drm/tinydrm/st7586.c
> > 
> > [snip]
> > 
> >> @@ -349,7 +349,7 @@ static int st7586_probe(struct spi_device *spi)
> >> 
> >>   	u32 rotation = 0;
> >>   	int ret;
> >> 
> >> -	mipi = devm_kzalloc(dev, sizeof(*mipi), GFP_KERNEL);
> >> +	mipi = kzalloc(sizeof(*mipi), GFP_KERNEL);
> > 
> > Ang here again.
> > 
> >>   	if (!mipi)
> >>   	
> >>   		return -ENOMEM;
> > 
> > [snip]

-- 
Regards,

Laurent Pinchart

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