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Message-ID: <619a8ad9-724c-16d0-482f-dc7cb75a44f6@suse.de>
Date: Thu, 31 Aug 2023 10:15:23 +0200
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Geert Uytterhoeven <geert@...ux-m68k.org>,
Daniel Stone <daniel@...ishbar.org>
Cc: Javier Martinez Canillas <javierm@...hat.com>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>, linux-kernel@...r.kernel.org,
dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v2 5/8] drm/client: Convert drm_client_buffer_addfb() to
drm_mode_addfb2()
Hi
Am 24.08.23 um 17:22 schrieb Geert Uytterhoeven:
> Hi Daniel,
>
> On Thu, Aug 24, 2023 at 5:12 PM Daniel Stone <daniel@...ishbar.org> wrote:
>> On Thu, 24 Aug 2023 at 16:09, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>>> struct drm_client_dev *client = buffer->client;
>>> - struct drm_mode_fb_cmd fb_req = { };
>>> - const struct drm_format_info *info;
>>> + struct drm_mode_fb_cmd2 fb_req = { };
>>> int ret;
>>>
>>> - info = drm_format_info(format);
>>> - fb_req.bpp = drm_format_info_bpp(info, 0);
>>> - fb_req.depth = info->depth;
>>> fb_req.width = width;
>>> fb_req.height = height;
>>> - fb_req.handle = handle;
>>> - fb_req.pitch = buffer->pitch;
>>> + fb_req.pixel_format = format;
>>> + fb_req.handles[0] = handle;
>>> + fb_req.pitches[0] = buffer->pitch;
>>>
>>> - ret = drm_mode_addfb(client->dev, &fb_req, client->file);
>>> + ret = drm_mode_addfb2(client->dev, &fb_req, client->file);
>>> if (ret)
>>> return ret;
>>
>> This should explicitly set the LINEAR modifier (and the modifier flag)
>> if the driver supports modifiers.
>
> Thanks for your comment!
>
> I have no idea how to do that, and I do not know what the impact
> would be. All I know is that the current implementation of
> drm_client_buffer_addfb() does not do that, so changing that in this
> patch would mean that this would no longer be a trivial conversion.
I agree. That change is too large and invasive for this patchset. Rather
add a comment or TODO item.
The correct way for adding the modifier is to extend the
drm_client_buffer_addfb() and pass in the information from the caller.
That caller is fbdev code. We currently detect the format from (bpp,
depth) values and forward the format to _addfb(). [1] Here we'd have to
check the driver for a modifier as well and forward it to _addfb()
[1]
https://elixir.bootlin.com/linux/v6.5/source/drivers/gpu/drm/drm_fbdev_generic.c#L88
The pair of (bpp, depth) values comes from __drm_fb_helper_find_sizes,
[2] which looks through the planes' formats and tries to find something
that fits the user's requested color mode. It would have to look for
modifiers as well. At some point, I want the helper to return formats
directly, but that's still a bit away.
[2]
https://elixir.bootlin.com/linux/v6.5/source/drivers/gpu/drm/drm_fb_helper.c#L1504
Best regards
Thomas
>
> Gr{oetje,eeting}s,
>
> Geert
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
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