diff mbox series

[v2,04/10] drm/simpledrm: Compute framebuffer stride if not set

Message ID 20220720142732.32041-5-tzimmermann@suse.de
State New
Headers show
Series drm: Add driver for PowerPC OF displays | expand

Commit Message

Thomas Zimmermann July 20, 2022, 2:27 p.m. UTC
Compute the framebuffer's scanline stride length if not given by
the simplefb data.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/tiny/simpledrm.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Javier Martinez Canillas July 25, 2022, 3:13 p.m. UTC | #1
Hello Geert,

On 7/21/22 16:46, Geert Uytterhoeven wrote:
> Hi Thomas,
> 
> On Wed, Jul 20, 2022 at 4:27 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>> Compute the framebuffer's scanline stride length if not given by
>> the simplefb data.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> 
> Thanks for your patch!
> 
>> --- a/drivers/gpu/drm/tiny/simpledrm.c
>> +++ b/drivers/gpu/drm/tiny/simpledrm.c
>> @@ -743,6 +743,9 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
>>                 drm_err(dev, "no simplefb configuration found\n");
>>                 return ERR_PTR(-ENODEV);
>>         }
>> +       if (!stride)
>> +               stride = format->cpp[0] * width;
> 
> DIV_ROUND_UP(drm_format_info_bpp(format) * width, 8)
>

I think you meant here:

DIV_ROUND_UP(drm_format_info_bpp(format, 0) * width, 8) ?
 
With that change,

Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Thomas Zimmermann July 27, 2022, 7:53 a.m. UTC | #2
Hi

Am 25.07.22 um 17:13 schrieb Javier Martinez Canillas:
> Hello Geert,
> 
> On 7/21/22 16:46, Geert Uytterhoeven wrote:
>> Hi Thomas,
>>
>> On Wed, Jul 20, 2022 at 4:27 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>> Compute the framebuffer's scanline stride length if not given by
>>> the simplefb data.
>>>
>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>>
>> Thanks for your patch!
>>
>>> --- a/drivers/gpu/drm/tiny/simpledrm.c
>>> +++ b/drivers/gpu/drm/tiny/simpledrm.c
>>> @@ -743,6 +743,9 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
>>>                  drm_err(dev, "no simplefb configuration found\n");
>>>                  return ERR_PTR(-ENODEV);
>>>          }
>>> +       if (!stride)
>>> +               stride = format->cpp[0] * width;
>>
>> DIV_ROUND_UP(drm_format_info_bpp(format) * width, 8)
>>
> 
> I think you meant here:
> 
> DIV_ROUND_UP(drm_format_info_bpp(format, 0) * width, 8) ?

I guess, that's the right function. My original code is correct, but cpp 
is also deprecated.

Best regards
Thomas

>   
> With that change,
> 
> Acked-by: Javier Martinez Canillas <javierm@redhat.com>
>
Daniel Vetter Aug. 11, 2022, 5:23 p.m. UTC | #3
On Wed, 27 Jul 2022 at 09:53, Thomas Zimmermann <tzimmermann@suse.de> wrote:
>
> Hi
>
> Am 25.07.22 um 17:13 schrieb Javier Martinez Canillas:
> > Hello Geert,
> >
> > On 7/21/22 16:46, Geert Uytterhoeven wrote:
> >> Hi Thomas,
> >>
> >> On Wed, Jul 20, 2022 at 4:27 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
> >>> Compute the framebuffer's scanline stride length if not given by
> >>> the simplefb data.
> >>>
> >>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> >>
> >> Thanks for your patch!
> >>
> >>> --- a/drivers/gpu/drm/tiny/simpledrm.c
> >>> +++ b/drivers/gpu/drm/tiny/simpledrm.c
> >>> @@ -743,6 +743,9 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
> >>>                  drm_err(dev, "no simplefb configuration found\n");
> >>>                  return ERR_PTR(-ENODEV);
> >>>          }
> >>> +       if (!stride)
> >>> +               stride = format->cpp[0] * width;
> >>
> >> DIV_ROUND_UP(drm_format_info_bpp(format) * width, 8)
> >>
> >
> > I think you meant here:
> >
> > DIV_ROUND_UP(drm_format_info_bpp(format, 0) * width, 8) ?
>
> I guess, that's the right function. My original code is correct, but cpp
> is also deprecated.

You all mean drm_format_info_min_pitch().

I really don't want drivers to go grab any of the legacy format info
fields like bpp or depth. switch() statements on the fourcc code for
programming registers, or one of the real helper functions in
drm_fourcc.c (there might be some gaps), but not ever going through
legacy concepts. Anything else just leads to subtle bugs when new
formats get added and oops suddenly the assumptions don't hold.

Those should be strictly limited to legacy (i.e. not drm_fourcc aware)
interfaces. Heck I think even fbdev emulation should completely switch
over to drm_fourcc/drm_format_info, but alas that's a pile of work and
not much payoff.

I'm trying to volunteer Same to add a legacy_bpp tag to the above
helper and appropriately limit it, I think limiting to formats with
depth!=0 is probably the right thing. And then we should probably
remove a pile of the cargo-culted depth!=0 entries too.
-Daniel

>
> Best regards
> Thomas
>
> >
> > With that change,
> >
> > Acked-by: Javier Martinez Canillas <javierm@redhat.com>
> >
>
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Ivo Totev
Thomas Zimmermann Aug. 11, 2022, 6:26 p.m. UTC | #4
Hi Daniel

Am 11.08.22 um 19:23 schrieb Daniel Vetter:
> On Wed, 27 Jul 2022 at 09:53, Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>
>> Hi
>>
>> Am 25.07.22 um 17:13 schrieb Javier Martinez Canillas:
>>> Hello Geert,
>>>
>>> On 7/21/22 16:46, Geert Uytterhoeven wrote:
>>>> Hi Thomas,
>>>>
>>>> On Wed, Jul 20, 2022 at 4:27 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>>>> Compute the framebuffer's scanline stride length if not given by
>>>>> the simplefb data.
>>>>>
>>>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>>>>
>>>> Thanks for your patch!
>>>>
>>>>> --- a/drivers/gpu/drm/tiny/simpledrm.c
>>>>> +++ b/drivers/gpu/drm/tiny/simpledrm.c
>>>>> @@ -743,6 +743,9 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
>>>>>                   drm_err(dev, "no simplefb configuration found\n");
>>>>>                   return ERR_PTR(-ENODEV);
>>>>>           }
>>>>> +       if (!stride)
>>>>> +               stride = format->cpp[0] * width;
>>>>
>>>> DIV_ROUND_UP(drm_format_info_bpp(format) * width, 8)
>>>>
>>>
>>> I think you meant here:
>>>
>>> DIV_ROUND_UP(drm_format_info_bpp(format, 0) * width, 8) ?
>>
>> I guess, that's the right function. My original code is correct, but cpp
>> is also deprecated.
> 
> You all mean drm_format_info_min_pitch().

Thanks a lot. I wasn't even aware of this function, but I had almost 
written my own implementation of it.  I'll update the patch accordingly.

Best regards
Thomas

> 
> I really don't want drivers to go grab any of the legacy format info
> fields like bpp or depth. switch() statements on the fourcc code for
> programming registers, or one of the real helper functions in
> drm_fourcc.c (there might be some gaps), but not ever going through
> legacy concepts. Anything else just leads to subtle bugs when new
> formats get added and oops suddenly the assumptions don't hold.
> 
> Those should be strictly limited to legacy (i.e. not drm_fourcc aware)
> interfaces. Heck I think even fbdev emulation should completely switch
> over to drm_fourcc/drm_format_info, but alas that's a pile of work and
> not much payoff.
> 
> I'm trying to volunteer Same to add a legacy_bpp tag to the above
> helper and appropriately limit it, I think limiting to formats with
> depth!=0 is probably the right thing. And then we should probably
> remove a pile of the cargo-culted depth!=0 entries too.
> -Daniel
> 
>>
>> Best regards
>> Thomas
>>
>>>
>>> With that change,
>>>
>>> Acked-by: Javier Martinez Canillas <javierm@redhat.com>
>>>
>>
>> --
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Software Solutions Germany GmbH
>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>> (HRB 36809, AG Nürnberg)
>> Geschäftsführer: Ivo Totev
> 
> 
>
Thomas Zimmermann Aug. 11, 2022, 6:27 p.m. UTC | #5
Am 11.08.22 um 20:26 schrieb Thomas Zimmermann:
> Hi Daniel
> 
> Am 11.08.22 um 19:23 schrieb Daniel Vetter:
>> On Wed, 27 Jul 2022 at 09:53, Thomas Zimmermann <tzimmermann@suse.de> 
>> wrote:
>>>
>>> Hi
>>>
>>> Am 25.07.22 um 17:13 schrieb Javier Martinez Canillas:
>>>> Hello Geert,
>>>>
>>>> On 7/21/22 16:46, Geert Uytterhoeven wrote:
>>>>> Hi Thomas,
>>>>>
>>>>> On Wed, Jul 20, 2022 at 4:27 PM Thomas Zimmermann 
>>>>> <tzimmermann@suse.de> wrote:
>>>>>> Compute the framebuffer's scanline stride length if not given by
>>>>>> the simplefb data.
>>>>>>
>>>>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>>>>>
>>>>> Thanks for your patch!
>>>>>
>>>>>> --- a/drivers/gpu/drm/tiny/simpledrm.c
>>>>>> +++ b/drivers/gpu/drm/tiny/simpledrm.c
>>>>>> @@ -743,6 +743,9 @@ static struct simpledrm_device 
>>>>>> *simpledrm_device_create(struct drm_driver *drv,
>>>>>>                   drm_err(dev, "no simplefb configuration found\n");
>>>>>>                   return ERR_PTR(-ENODEV);
>>>>>>           }
>>>>>> +       if (!stride)
>>>>>> +               stride = format->cpp[0] * width;
>>>>>
>>>>> DIV_ROUND_UP(drm_format_info_bpp(format) * width, 8)
>>>>>
>>>>
>>>> I think you meant here:
>>>>
>>>> DIV_ROUND_UP(drm_format_info_bpp(format, 0) * width, 8) ?
>>>
>>> I guess, that's the right function. My original code is correct, but cpp
>>> is also deprecated.
>>
>> You all mean drm_format_info_min_pitch().
> 
> Thanks a lot. I wasn't even aware of this function, but I had almost 
> written my own implementation of it.  I'll update the patch accordingly.

Arghh, too late. I merged that patch already.

> 
> Best regards
> Thomas
> 
>>
>> I really don't want drivers to go grab any of the legacy format info
>> fields like bpp or depth. switch() statements on the fourcc code for
>> programming registers, or one of the real helper functions in
>> drm_fourcc.c (there might be some gaps), but not ever going through
>> legacy concepts. Anything else just leads to subtle bugs when new
>> formats get added and oops suddenly the assumptions don't hold.
>>
>> Those should be strictly limited to legacy (i.e. not drm_fourcc aware)
>> interfaces. Heck I think even fbdev emulation should completely switch
>> over to drm_fourcc/drm_format_info, but alas that's a pile of work and
>> not much payoff.
>>
>> I'm trying to volunteer Same to add a legacy_bpp tag to the above
>> helper and appropriately limit it, I think limiting to formats with
>> depth!=0 is probably the right thing. And then we should probably
>> remove a pile of the cargo-culted depth!=0 entries too.
>> -Daniel
>>
>>>
>>> Best regards
>>> Thomas
>>>
>>>>
>>>> With that change,
>>>>
>>>> Acked-by: Javier Martinez Canillas <javierm@redhat.com>
>>>>
>>>
>>> -- 
>>> Thomas Zimmermann
>>> Graphics Driver Developer
>>> SUSE Software Solutions Germany GmbH
>>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>>> (HRB 36809, AG Nürnberg)
>>> Geschäftsführer: Ivo Totev
>>
>>
>>
>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
index 7de477835d44..cff9e7f71f80 100644
--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c
@@ -743,6 +743,9 @@  static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
 		drm_err(dev, "no simplefb configuration found\n");
 		return ERR_PTR(-ENODEV);
 	}
+	if (!stride)
+		stride = format->cpp[0] * width;
+
 	sdev->mode = simpledrm_mode(width, height);
 	sdev->format = format;
 	sdev->pitch = stride;