Re: [PATCH 1/3] drm/omap: Pass along the format info from .fb_create() to drm_helper_mode_fill_fb_struct()

[Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>]

Hi,

On 05/08/2025 17:49, Imre Deak wrote:
> Hi Tomi,
> 
> On Tue, Aug 05, 2025 at 02:53:36PM +0300, Tomi Valkeinen wrote:
>> Hi Imre,
>>
>> On 28/07/2025 13:16, Imre Deak wrote:
>>> Plumb the format info from .fb_create() all the way to
>>> drm_helper_mode_fill_fb_struct() to avoid the redundant
>>> lookup.
>>>
>>> For the fbdev case a manual drm_get_format_info() lookup
>>> is needed.
>>>
>>> The patch is based on the driver parts of the patchset at Link:
>>> below, which missed converting the omap driver.
>>>
>>> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>> Cc: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>>> Cc: Thomas Zimmermann <tzimmermann@suse.de>
>>> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>>> Cc: Maxime Ripard <mripard@kernel.org>
>>> Fixes: 41ab92d35ccd ("drm: Make passing of format info to drm_helper_mode_fill_fb_struct() mandatory")
>>> Reported-by: Mark Brown <broonie@kernel.org>
>>> Closes: https://lore.kernel.org/all/98b3a62c-91ff-4f91-a58b-e1265f84180b@sirena.org.uk
>>> Link: https://lore.kernel.org/all/20250701090722.13645-1-ville.syrjala@linux.intel.com
>>> Signed-off-by: Imre Deak <imre.deak@intel.com>
>>> ---
>>>  drivers/gpu/drm/omapdrm/omap_fb.c    | 23 ++++++++++-------------
>>>  drivers/gpu/drm/omapdrm/omap_fb.h    |  2 ++
>>>  drivers/gpu/drm/omapdrm/omap_fbdev.c |  5 ++++-
>>>  3 files changed, 16 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/omapdrm/omap_fb.c b/drivers/gpu/drm/omapdrm/omap_fb.c
>>> index 30c81e2e5d6b3..bb3105556f193 100644
>>> --- a/drivers/gpu/drm/omapdrm/omap_fb.c
>>> +++ b/drivers/gpu/drm/omapdrm/omap_fb.c
>>> @@ -351,7 +351,7 @@ struct drm_framebuffer *omap_framebuffer_create(struct drm_device *dev,
>>>  		}
>>>  	}
>>>  
>>> -	fb = omap_framebuffer_init(dev, mode_cmd, bos);
>>> +	fb = omap_framebuffer_init(dev, info, mode_cmd, bos);
>>>  	if (IS_ERR(fb))
>>>  		goto error;
>>>  
>>> @@ -365,9 +365,9 @@ struct drm_framebuffer *omap_framebuffer_create(struct drm_device *dev,
>>>  }
>>>  
>>>  struct drm_framebuffer *omap_framebuffer_init(struct drm_device *dev,
>>> +		const struct drm_format_info *info,
>>>  		const struct drm_mode_fb_cmd2 *mode_cmd, struct drm_gem_object **bos)
>>>  {
>>> -	const struct drm_format_info *format = NULL;
>>>  	struct omap_framebuffer *omap_fb = NULL;
>>>  	struct drm_framebuffer *fb = NULL;
>>>  	unsigned int pitch = mode_cmd->pitches[0];
>>> @@ -377,15 +377,12 @@ struct drm_framebuffer *omap_framebuffer_init(struct drm_device *dev,
>>>  			dev, mode_cmd, mode_cmd->width, mode_cmd->height,
>>>  			(char *)&mode_cmd->pixel_format);
>>>  
>>> -	format = drm_get_format_info(dev, mode_cmd->pixel_format,
>>> -				     mode_cmd->modifier[0]);
>>> -
>>>  	for (i = 0; i < ARRAY_SIZE(formats); i++) {
>>>  		if (formats[i] == mode_cmd->pixel_format)
>>>  			break;
>>>  	}
>>>  
>>> -	if (!format || i == ARRAY_SIZE(formats)) {
>>> +	if (i == ARRAY_SIZE(formats)) {
>>>  		dev_dbg(dev->dev, "unsupported pixel format: %4.4s\n",
>>>  			(char *)&mode_cmd->pixel_format);
>>>  		ret = -EINVAL;
>>> @@ -399,7 +396,7 @@ struct drm_framebuffer *omap_framebuffer_init(struct drm_device *dev,
>>>  	}
>>>  
>>>  	fb = &omap_fb->base;
>>> -	omap_fb->format = format;
>>> +	omap_fb->format = info;
>>>  	mutex_init(&omap_fb->lock);
>>>  
>>>  	/*
>>> @@ -407,23 +404,23 @@ struct drm_framebuffer *omap_framebuffer_init(struct drm_device *dev,
>>>  	 * that the two planes of multiplane formats need the same number of
>>>  	 * bytes per pixel.
>>>  	 */
>>> -	if (format->num_planes == 2 && pitch != mode_cmd->pitches[1]) {
>>> +	if (info->num_planes == 2 && pitch != mode_cmd->pitches[1]) {
>>>  		dev_dbg(dev->dev, "pitches differ between planes 0 and 1\n");
>>>  		ret = -EINVAL;
>>>  		goto fail;
>>>  	}
>>>  
>>> -	if (pitch % format->cpp[0]) {
>>> +	if (pitch % info->cpp[0]) {
>>>  		dev_dbg(dev->dev,
>>>  			"buffer pitch (%u bytes) is not a multiple of pixel size (%u bytes)\n",
>>> -			pitch, format->cpp[0]);
>>> +			pitch, info->cpp[0]);
>>>  		ret = -EINVAL;
>>>  		goto fail;
>>>  	}
>>>  
>>> -	for (i = 0; i < format->num_planes; i++) {
>>> +	for (i = 0; i < info->num_planes; i++) {
>>>  		struct plane *plane = &omap_fb->planes[i];
>>> -		unsigned int vsub = i == 0 ? 1 : format->vsub;
>>> +		unsigned int vsub = i == 0 ? 1 : info->vsub;
>>>  		unsigned int size;
>>>  
>>>  		size = pitch * mode_cmd->height / vsub;
>>> @@ -440,7 +437,7 @@ struct drm_framebuffer *omap_framebuffer_init(struct drm_device *dev,
>>>  		plane->dma_addr  = 0;
>>>  	}
>>>  
>>> -	drm_helper_mode_fill_fb_struct(dev, fb, NULL, mode_cmd);
>>> +	drm_helper_mode_fill_fb_struct(dev, fb, info, mode_cmd);
>>
>> Isn't the fix really a one-liner, just passing "format" here instead of
>> NULL?
> 
> That would fix the issue of fb->format being initialized to NULL yes.
> 
> However, I think the change should be in sync with the conversion of the
> rest of the drivers in patchset [1]. IOW, what this patch is meant to
> fix is that [1] missed converting the OMAP driver similarly to the other
> drivers.
> 
> I think the change is equivalent to the above one-liner you suggest with
> the following differences:
> 
> - omap_framebuffer_init() uses the drm_format_info passed down from either
>   drm_internal_framebuffer_create(), or omap_fbdev_driver_fbdev_probe().
>   In both cases the passed down format info matches what
>   omap_framebuffer_init() would look up again.
> 
> - Skip the format == NULL check. format can't be NULL in any case, since
>   that would have emitted a WARN already in drm_get_format_info() ->
>   drm_format_info().
> 
> [1] https://lore.kernel.org/all/20250701090722.13645-1-ville.syrjala@linux.intel.com

Yep, I have no issue with the patch as such. But if it's a fix, going
into an rc, I think it's better if it's as small as possible, and do the
cleanups/refactorings as a non-fix later.

The patch description here sounds more like it's just refactoring the
code a bit, but if I understand correctly, it's fixing an issue that
cause a WARN?

So... Either we could 1) split the patch, have the WARN fix as a fix
patch to the current rc, and the rest later in the next merge window, or
2) if you want to keep this as a single patch, I think it makes sense to
change the subject and description to highlight the fix aspect.

I think my comments apply to all patches in this series, as they're
essentially doing the same thing...

 Tomi

>>  Tomi
>>
>>>  
>>>  	ret = drm_framebuffer_init(dev, fb, &omap_framebuffer_funcs);
>>>  	if (ret) {
>>> diff --git a/drivers/gpu/drm/omapdrm/omap_fb.h b/drivers/gpu/drm/omapdrm/omap_fb.h
>>> index 0873f953cf1d1..e6010302a22bd 100644
>>> --- a/drivers/gpu/drm/omapdrm/omap_fb.h
>>> +++ b/drivers/gpu/drm/omapdrm/omap_fb.h
>>> @@ -13,6 +13,7 @@ struct drm_connector;
>>>  struct drm_device;
>>>  struct drm_file;
>>>  struct drm_framebuffer;
>>> +struct drm_format_info;
>>>  struct drm_gem_object;
>>>  struct drm_mode_fb_cmd2;
>>>  struct drm_plane_state;
>>> @@ -23,6 +24,7 @@ struct drm_framebuffer *omap_framebuffer_create(struct drm_device *dev,
>>>  		struct drm_file *file, const struct drm_format_info *info,
>>>  		const struct drm_mode_fb_cmd2 *mode_cmd);
>>>  struct drm_framebuffer *omap_framebuffer_init(struct drm_device *dev,
>>> +		const struct drm_format_info *info,
>>>  		const struct drm_mode_fb_cmd2 *mode_cmd, struct drm_gem_object **bos);
>>>  int omap_framebuffer_pin(struct drm_framebuffer *fb);
>>>  void omap_framebuffer_unpin(struct drm_framebuffer *fb);
>>> diff --git a/drivers/gpu/drm/omapdrm/omap_fbdev.c b/drivers/gpu/drm/omapdrm/omap_fbdev.c
>>> index 7b63968906817..948af7ec1130b 100644
>>> --- a/drivers/gpu/drm/omapdrm/omap_fbdev.c
>>> +++ b/drivers/gpu/drm/omapdrm/omap_fbdev.c
>>> @@ -197,7 +197,10 @@ int omap_fbdev_driver_fbdev_probe(struct drm_fb_helper *helper,
>>>  		goto fail;
>>>  	}
>>>  
>>> -	fb = omap_framebuffer_init(dev, &mode_cmd, &bo);
>>> +	fb = omap_framebuffer_init(dev,
>>> +				   drm_get_format_info(dev, mode_cmd.pixel_format,
>>> +						       mode_cmd.modifier[0]),
>>> +				   &mode_cmd, &bo);
>>>  	if (IS_ERR(fb)) {
>>>  		dev_err(dev->dev, "failed to allocate fb\n");
>>>  		/* note: if fb creation failed, we can't rely on fb destroy
>>