From: Thomas Zimmermann <tzimmermann@suse.de>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
David Airlie <airlied@linux.ie>,
Michael Ellerman <mpe@ellerman.id.au>,
Helge Deller <deller@gmx.de>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>,
Javier Martinez Canillas <javierm@redhat.com>,
DRI Development <dri-devel@lists.freedesktop.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Maxime Ripard <maxime@cerno.tech>,
Paul Mackerras <paulus@samba.org>,
Michal Suchanek <msuchanek@suse.de>,
Sam Ravnborg <sam@ravnborg.org>
Subject: Re: [PATCH v2 04/10] drm/simpledrm: Compute framebuffer stride if not set
Date: Thu, 11 Aug 2022 20:26:01 +0200 [thread overview]
Message-ID: <33ce5744-5d41-2501-6105-2585529820d2@suse.de> (raw)
In-Reply-To: <CAKMK7uGr_SbHAm7r5VNWgpM2cPMFYpCmyE_Aq8TYc84rOAtJpA@mail.gmail.com>
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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
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
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next prev parent reply other threads:[~2022-08-11 18:26 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-20 14:27 [PATCH v2 00/10] drm: Add driver for PowerPC OF displays Thomas Zimmermann
2022-07-20 14:27 ` [PATCH v2 01/10] drm/simpledrm: Remove mem field from device structure Thomas Zimmermann
2022-07-25 14:48 ` Javier Martinez Canillas
2022-07-20 14:27 ` [PATCH v2 02/10] drm/simpledrm: Inline device-init helpers Thomas Zimmermann
2022-07-25 15:01 ` Javier Martinez Canillas
2022-07-27 7:50 ` Thomas Zimmermann
2022-07-27 9:30 ` Javier Martinez Canillas
2022-07-20 14:27 ` [PATCH v2 03/10] drm/simpledrm: Remove pdev field from device structure Thomas Zimmermann
2022-07-25 15:02 ` Javier Martinez Canillas
2022-07-20 14:27 ` [PATCH v2 04/10] drm/simpledrm: Compute framebuffer stride if not set Thomas Zimmermann
2022-07-21 14:46 ` Geert Uytterhoeven
2022-07-25 15:13 ` Javier Martinez Canillas
2022-07-27 7:53 ` Thomas Zimmermann
2022-08-11 17:23 ` Daniel Vetter
2022-08-11 18:26 ` Thomas Zimmermann [this message]
2022-08-11 18:27 ` Thomas Zimmermann
2022-09-06 19:16 ` Daniel Vetter
2022-07-20 14:27 ` [PATCH v2 05/10] drm/simpledrm: Convert to atomic helpers Thomas Zimmermann
2022-07-25 15:46 ` Javier Martinez Canillas
2022-07-27 7:58 ` Thomas Zimmermann
2022-07-20 14:27 ` [PATCH v2 06/10] drm/simpledrm: Move some functionality into fwfb helper library Thomas Zimmermann
2022-07-25 16:23 ` Javier Martinez Canillas
2022-07-27 8:24 ` Thomas Zimmermann
2022-07-27 9:39 ` Javier Martinez Canillas
2022-07-20 14:27 ` [PATCH v2 07/10] drm/ofdrm: Add ofdrm for Open Firmware framebuffers Thomas Zimmermann
2022-07-26 13:17 ` Javier Martinez Canillas
2022-09-21 11:41 ` Thomas Zimmermann
2022-07-20 14:27 ` [PATCH v2 08/10] drm/ofdrm: Add CRTC state Thomas Zimmermann
2022-07-26 13:36 ` Javier Martinez Canillas
2022-09-21 11:45 ` Thomas Zimmermann
2022-07-20 14:27 ` [PATCH v2 09/10] drm/ofdrm: Add per-model device function Thomas Zimmermann
2022-07-26 13:38 ` Javier Martinez Canillas
2022-07-26 14:40 ` Michal Suchánek
2022-07-26 19:22 ` Javier Martinez Canillas
2022-07-27 8:33 ` Thomas Zimmermann
2022-08-05 0:22 ` Benjamin Herrenschmidt
2022-09-21 12:37 ` Thomas Zimmermann
2022-07-20 14:27 ` [PATCH v2 10/10] drm/ofdrm: Support color management Thomas Zimmermann
2022-07-26 13:49 ` Javier Martinez Canillas
2022-07-27 8:41 ` Thomas Zimmermann
2022-07-27 9:45 ` Javier Martinez Canillas
2022-08-05 0:29 ` Benjamin Herrenschmidt
2022-08-05 0:19 ` Benjamin Herrenschmidt
2022-09-21 12:55 ` Thomas Zimmermann
2022-09-21 16:48 ` Geert Uytterhoeven
2022-09-22 6:42 ` Thomas Zimmermann
2022-09-22 7:28 ` Maxime Ripard
2022-09-22 8:06 ` Thomas Zimmermann
2022-07-28 11:13 ` [PATCH v2 00/10] drm: Add driver for PowerPC OF displays Michael Ellerman
2022-07-28 11:31 ` Michal Suchánek
2022-07-28 11:42 ` Thomas Zimmermann
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