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Message-ID: <87r0pau99o.fsf@minerva.mail-host-address-is-not-set>
Date: Fri, 14 Jul 2023 11:34:11 +0200
From: Javier Martinez Canillas <javierm@...hat.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>,
linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 1/8] drm/ssd130x: Fix pitch calculation in
ssd130x_fb_blit_rect()
Geert Uytterhoeven <geert@...ux-m68k.org> writes:
Hello Geert,
Thanks for your patch!
> The page height must be taken into account only for vertical coordinates
> and heights, not for horizontal coordinates and widths.
>
> Fixes: 179a790aaf2a0127 ("drm/ssd130x: Set the page height value in the device info data")
> Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> ---
> drivers/gpu/drm/solomon/ssd130x.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
> index afb08a8aa9fcdaf2..b4c376962629580b 100644
> --- a/drivers/gpu/drm/solomon/ssd130x.c
> +++ b/drivers/gpu/drm/solomon/ssd130x.c
> @@ -596,7 +596,7 @@ static int ssd130x_fb_blit_rect(struct drm_framebuffer *fb, const struct iosys_m
> rect->y1 = round_down(rect->y1, page_height);
> rect->y2 = min_t(unsigned int, round_up(rect->y2, page_height), ssd130x->height);
>
> - dst_pitch = DIV_ROUND_UP(drm_rect_width(rect), page_height);
> + dst_pitch = DIV_ROUND_UP(drm_rect_width(rect), 8);
>
That's true for ssd130x controllers that use R1, but when doing that
change one of my goals was to prepare the driver for supporting the
ssd132x family that use a 16-grayscale pixel format (R4).
For those controllers, the pixels are encoded in 4-bit and each page
has two pixels. So for those controllers the dst_pitch will need to
be DIV_ROUND_UP(drm_rect_width(rect), 2) instead since the width is
not 8 in that case.
So I would prefer to skip this patch from your set, because otherwise
we will need to revert it when adding support for SSD132x controllers.
--
Best regards,
Javier Martinez Canillas
Core Platforms
Red Hat
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