From: Thomas Zimmermann <tzimmermann@suse.de>
To: Javier Martinez Canillas <javierm@redhat.com>,
linux-kernel@vger.kernel.org
Cc: linux-fbdev@vger.kernel.org, "David Airlie" <airlied@linux.ie>,
"Daniel Vetter" <daniel.vetter@ffwll.ch>,
dri-devel@lists.freedesktop.org,
"Noralf Trønnes" <noralf@tronnes.org>,
"Geert Uytterhoeven" <geert@linux-m68k.org>,
"Maxime Ripard" <maxime@cerno.tech>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
"Sam Ravnborg" <sam@ravnborg.org>
Subject: Re: [PATCH v2 1/4] drm/format-helper: Add drm_fb_{xrgb8888,gray8}_to_mono_reversed()
Date: Fri, 4 Feb 2022 17:00:16 +0100 [thread overview]
Message-ID: <22cf9951-dc85-18b1-94fb-8387f76a94ab@suse.de> (raw)
In-Reply-To: <47100413-db63-1efa-45e9-028dfc430b7e@suse.de>
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Am 04.02.22 um 16:52 schrieb Thomas Zimmermann:
[...]
>> +/**
>> + * drm_fb_xrgb8888_to_mono_reversed - Convert XRGB8888 to reversed
>> monochrome
>> + * @dst: reversed monochrome destination buffer
>> + * @dst_pitch: Number of bytes between two consecutive scanlines
>> within dst
>> + * @src: XRGB8888 source buffer
>> + * @fb: DRM framebuffer
>> + * @clip: Clip rectangle area to copy
>> + *
>> + * DRM doesn't have native monochrome support.
>> + * Such drivers can announce the commonly supported XR24 format to
>> userspace
>> + * and use this function to convert to the native format.
>> + *
>> + * This function uses drm_fb_xrgb8888_to_gray8() to convert to
>> grayscale and
>> + * then the result is converted from grayscale to reversed monohrome.
>> + */
>> +void drm_fb_xrgb8888_to_mono_reversed(void *dst, unsigned int
>> dst_pitch, const void *src,
>> + const struct drm_framebuffer *fb,
>> + const struct drm_rect *clip)
>> +{
>> + if (WARN_ON(fb->format->format != DRM_FORMAT_XRGB8888))
>> + return;
>> +
>> + if (!dst_pitch)
>> + dst_pitch = drm_rect_width(clip);
>> +
>> + drm_fb_xrgb8888_to_gray8(dst, dst_pitch, src, fb, clip);
>> + drm_fb_gray8_to_mono_reversed(dst, dst_pitch, dst, fb, clip);
>
> Converting from dst into dst can give incorrect results. At some point
> we probably want to add restrict qualifiers to these pointers, to help
> the compiler with optimizing.
>
> A better approach here is to pull the per-line conversion from
> drm_fb_xrgb8888_to_gray8() into a separate helper and implement a
> line-by-line conversion here. something like this:
>
> drm_fb_xrgb8888_to_mono_reversed()
> {
> char *tmp = kmalloc(size of a single line of gray8)
>
> for (heigth) {
> drm_fb_xrgb8888_to_gray8_line(tmp, ..., src, ...);
> drm_fb_gray8_to_mono_reversed(dst, ..., tmp, ...);
Here, I meant 'drm_fb_gray8_to_mono_reversed_line()'
>
> src += fb->pitches[0]
> dst += dst_pitch;
> }
>
> kfree(tmp);
> }
To elaborate, this is an example of what I meant by composable. In the
future, we can generalize this function and hand-in 2 function pointers
the do the conversion with tmp as intermediate buffer. That would work
for any combination of formats that have a common intermediate format.
>
> Best regards
> Thomas
>
>> +}
>> +EXPORT_SYMBOL(drm_fb_xrgb8888_to_mono_reversed);
>> diff --git a/include/drm/drm_format_helper.h
>> b/include/drm/drm_format_helper.h
>> index b30ed5de0a33..85e551a5cbe6 100644
>> --- a/include/drm/drm_format_helper.h
>> +++ b/include/drm/drm_format_helper.h
>> @@ -43,4 +43,11 @@ int drm_fb_blit_toio(void __iomem *dst, unsigned
>> int dst_pitch, uint32_t dst_for
>> const void *vmap, const struct drm_framebuffer *fb,
>> const struct drm_rect *rect);
>> +void drm_fb_gray8_to_mono_reversed(void *dst, unsigned int dst_pitch,
>> const void *src,
>> + const struct drm_rect *clip);
>> +
>> +void drm_fb_xrgb8888_to_mono_reversed(void *dst, unsigned int
>> dst_pitch, const void *src,
>> + const struct drm_framebuffer *fb,
>> + const struct drm_rect *clip);
>> +
>> #endif /* __LINUX_DRM_FORMAT_HELPER_H */
>
--
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:[~2022-02-04 16:00 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-04 13:43 [PATCH v2 0/4] drm/tiny: Add driver for Solomon SSD1307 OLED displays Javier Martinez Canillas
2022-02-04 13:43 ` [PATCH v2 1/4] drm/format-helper: Add drm_fb_{xrgb8888,gray8}_to_mono_reversed() Javier Martinez Canillas
2022-02-04 15:52 ` Thomas Zimmermann
2022-02-04 16:00 ` Thomas Zimmermann [this message]
2022-02-04 19:31 ` Javier Martinez Canillas
2022-02-04 20:35 ` Thomas Zimmermann
2022-02-04 21:02 ` Ilia Mirkin
2022-02-07 12:44 ` [PATCH v2 1/4] drm/format-helper: Add drm_fb_{xrgb8888, gray8}_to_mono_reversed() Thomas Zimmermann
2022-02-04 13:43 ` [PATCH v2 2/4] drm/tiny: Add driver for Solomon SSD130X OLED displays Javier Martinez Canillas
2022-02-04 14:26 ` Andy Shevchenko
2022-02-04 19:19 ` Javier Martinez Canillas
2022-02-05 13:04 ` Andy Shevchenko
2022-02-05 17:40 ` Javier Martinez Canillas
2022-02-04 13:43 ` [PATCH v2 3/4] MAINTAINERS: Add entry for Solomon SSD130X OLED displays DRM driver Javier Martinez Canillas
2022-02-04 13:57 ` Andy Shevchenko
2022-02-04 14:12 ` Javier Martinez Canillas
2022-02-04 14:28 ` Andy Shevchenko
2022-02-04 14:33 ` Javier Martinez Canillas
2022-02-04 13:43 ` [PATCH v2 4/4] dt-bindings: display: ssd1307fb: Add myself as binding co-maintainer Javier Martinez Canillas
2022-02-09 22:14 ` Rob Herring
2022-02-04 14:31 ` [PATCH v2 0/4] drm/tiny: Add driver for Solomon SSD1307 OLED displays Geert Uytterhoeven
2022-02-04 14:37 ` Javier Martinez Canillas
2022-02-08 14:19 ` Geert Uytterhoeven
2022-02-08 15:10 ` Javier Martinez Canillas
2022-02-08 15:18 ` Mark Brown
2022-02-08 15:32 ` Javier Martinez Canillas
2022-02-08 15:23 ` Geert Uytterhoeven
2022-02-08 15:40 ` Javier Martinez Canillas
2022-02-08 17:19 ` Javier Martinez Canillas
2022-02-09 13:47 ` Andy Shevchenko
2022-02-09 14:27 ` Geert Uytterhoeven
2022-02-09 14:42 ` Javier Martinez Canillas
2022-02-09 15:32 ` Andy Shevchenko
2022-02-10 8:32 ` Maxime Ripard
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