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From: "Pierre Asselin" <pa@panix.com>
To: "Javier Martinez Canillas" <javierm@redhat.com>
Cc: "Pierre Asselin" <pa@panix.com>,
	"Jocelyn Falempe" <jfalempe@redhat.com>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	"Hans de Goede" <hdegoede@redhat.com>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"Ard Biesheuvel" <ardb@kernel.org>
Subject: Re: [PATCH] firmware/sysfb: Fix wrong stride when bits-per-pixel is calculated
Date: Wed, 12 Apr 2023 17:53:25 -0400	[thread overview]
Message-ID: <40edb0fdb0eaff434f4872dd677923a6.squirrel@mail.panix.com> (raw)
In-Reply-To: <87cz48srs4.fsf@minerva.mail-host-address-is-not-set>

> Javier Martinez Canillas <javierm@redhat.com> writes:
>
> I still don't understand why this particular configuration didn't work...
>
> The framebuffer starts at 0xd8000000 and has a size of 0x240000 bytes, so

Says who ?  It's the same grub, same video mode as before the regression,
so the size is probably 0x300000 like it always was.

> a r8g8b8 pixel format with resolution 1024x768 should be correct. Since is
> 1024 * 768 * (24 / 8) = 2359296 = 0x240000.

That is internally consistent, but at variance with the video mode
set up by grub.

It is better to sqeeze bits by 4:3 on each line (regression) than to
scatter 4 logical lines across 3 physical lines (regression, patched) !

> Could you please apply the following diff that will print all the relevant
> fields from the screen_info that are used to calculate the bpp and stride.

YES !  I can't peer into that struct screen_info and I don't know to
write the printk's.  (Hm, doesn't look too hard, but trust me, I would
fumble it.)

I'll back out the original patch first.
Stand by.

--PA


  reply	other threads:[~2023-04-12 21:53 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-12 15:02 [PATCH] firmware/sysfb: Fix wrong stride when bits-per-pixel is calculated Javier Martinez Canillas
2023-04-12 16:18 ` Pierre Asselin
2023-04-12 17:31   ` Javier Martinez Canillas
2023-04-12 18:12     ` Pierre Asselin
2023-04-12 18:24       ` Javier Martinez Canillas
2023-04-12 18:51         ` Pierre Asselin
2023-04-12 21:04           ` Javier Martinez Canillas
2023-04-12 21:40             ` Javier Martinez Canillas
2023-04-12 21:53               ` Pierre Asselin [this message]
2023-04-12 22:09                 ` Javier Martinez Canillas
2023-04-12 23:13                   ` Pierre Asselin
2023-04-13  1:13                     ` Pierre Asselin
2023-04-13  1:34                       ` Pierre Asselin
2023-04-17  8:15                         ` Thomas Zimmermann
2023-04-17  8:58                           ` Javier Martinez Canillas
2023-04-17  9:15                             ` Thomas Zimmermann
2023-04-17  9:29                               ` Javier Martinez Canillas
2023-04-13  7:08                       ` Javier Martinez Canillas
2023-04-13 16:24                         ` Pierre Asselin
2023-04-13 16:34                           ` Javier Martinez Canillas
2023-04-13 17:17                         ` Pierre Asselin
2023-04-13 18:04                           ` Javier Martinez Canillas
2023-04-13  6:54                     ` Javier Martinez Canillas

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