linux-kernel - Re: [PATCH v3 2/3] drm/format-helper: Add drm_fb_xrgb8888_to_xrgb2101010

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Date:   Mon, 13 Dec 2021 09:15:57 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Hector Martin <marcan@...can.st>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Hans de Goede <hdegoede@...hat.com>
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        Javier Martinez Canillas <javier@...hile0.org>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>
Subject: Re: [PATCH v3 2/3] drm/format-helper: Add
 drm_fb_xrgb8888_to_xrgb2101010_toio()



Am 12.12.21 um 07:24 schrieb Hector Martin:
> Add XRGB8888 emulation support for devices that can only do XRGB2101010.
> 
> This is chiefly useful for simpledrm on Apple devices where the
> bootloader-provided framebuffer is 10-bit.
> 
> Signed-off-by: Hector Martin <marcan@...can.st>

Reviewed-by: Thomas Zimmermann <tzimmermann@...e.de>

> ---
>   drivers/gpu/drm/drm_format_helper.c | 64 +++++++++++++++++++++++++++++
>   include/drm/drm_format_helper.h     |  3 ++
>   2 files changed, 67 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
> index dbe3e830096e..0f28dd2bdd72 100644
> --- a/drivers/gpu/drm/drm_format_helper.c
> +++ b/drivers/gpu/drm/drm_format_helper.c
> @@ -409,6 +409,61 @@ void drm_fb_xrgb8888_to_rgb888_toio(void __iomem *dst, unsigned int dst_pitch,
>   }
>   EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb888_toio);
>   
> +static void drm_fb_xrgb8888_to_xrgb2101010_line(u32 *dbuf, const u32 *sbuf,
> +						unsigned int pixels)
> +{
> +	unsigned int x;
> +	u32 val32;
> +
> +	for (x = 0; x < pixels; x++) {
> +		val32 = ((sbuf[x] & 0x000000FF) << 2) |
> +			((sbuf[x] & 0x0000FF00) << 4) |
> +			((sbuf[x] & 0x00FF0000) << 6);
> +		*dbuf++ = val32 | ((val32 >> 8) & 0x00300C03);
> +	}
> +}
> +
> +/**
> + * drm_fb_xrgb8888_to_xrgb2101010_toio - Convert XRGB8888 to XRGB2101010 clip
> + * buffer
> + * @dst: XRGB2101010 destination buffer (iomem)
> + * @dst_pitch: Number of bytes between two consecutive scanlines within dst
> + * @vaddr: XRGB8888 source buffer
> + * @fb: DRM framebuffer
> + * @clip: Clip rectangle area to copy
> + *
> + * Drivers can use this function for XRGB2101010 devices that don't natively
> + * support XRGB8888.
> + */
> +void drm_fb_xrgb8888_to_xrgb2101010_toio(void __iomem *dst,
> +					 unsigned int dst_pitch, const void *vaddr,
> +					 const struct drm_framebuffer *fb,
> +					 const struct drm_rect *clip)
> +{
> +	size_t linepixels = clip->x2 - clip->x1;
> +	size_t dst_len = linepixels * sizeof(u32);
> +	unsigned int y, lines = clip->y2 - clip->y1;
> +	void *dbuf;
> +
> +	if (!dst_pitch)
> +		dst_pitch = dst_len;
> +
> +	dbuf = kmalloc(dst_len, GFP_KERNEL);
> +	if (!dbuf)
> +		return;
> +
> +	vaddr += clip_offset(clip, fb->pitches[0], sizeof(u32));
> +	for (y = 0; y < lines; y++) {
> +		drm_fb_xrgb8888_to_xrgb2101010_line(dbuf, vaddr, linepixels);
> +		memcpy_toio(dst, dbuf, dst_len);
> +		vaddr += fb->pitches[0];
> +		dst += dst_pitch;
> +	}
> +
> +	kfree(dbuf);
> +}
> +EXPORT_SYMBOL(drm_fb_xrgb8888_to_xrgb2101010_toio);
> +
>   /**
>    * drm_fb_xrgb8888_to_gray8 - Convert XRGB8888 to grayscale
>    * @dst: 8-bit grayscale destination buffer
> @@ -500,6 +555,10 @@ int drm_fb_blit_toio(void __iomem *dst, unsigned int dst_pitch, uint32_t dst_for
>   		fb_format = DRM_FORMAT_XRGB8888;
>   	if (dst_format == DRM_FORMAT_ARGB8888)
>   		dst_format = DRM_FORMAT_XRGB8888;
> +	if (fb_format == DRM_FORMAT_ARGB2101010)
> +		fb_format = DRM_FORMAT_XRGB2101010;
> +	if (dst_format == DRM_FORMAT_ARGB2101010)
> +		dst_format = DRM_FORMAT_XRGB2101010;
>   
>   	if (dst_format == fb_format) {
>   		drm_fb_memcpy_toio(dst, dst_pitch, vmap, fb, clip);
> @@ -515,6 +574,11 @@ int drm_fb_blit_toio(void __iomem *dst, unsigned int dst_pitch, uint32_t dst_for
>   			drm_fb_xrgb8888_to_rgb888_toio(dst, dst_pitch, vmap, fb, clip);
>   			return 0;
>   		}
> +	} else if (dst_format == DRM_FORMAT_XRGB2101010) {
> +		if (fb_format == DRM_FORMAT_XRGB8888) {
> +			drm_fb_xrgb8888_to_xrgb2101010_toio(dst, dst_pitch, vmap, fb, clip);
> +			return 0;
> +		}
>   	}
>   
>   	return -EINVAL;
> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
> index 97e4c3223af3..b30ed5de0a33 100644
> --- a/include/drm/drm_format_helper.h
> +++ b/include/drm/drm_format_helper.h
> @@ -33,6 +33,9 @@ void drm_fb_xrgb8888_to_rgb888(void *dst, unsigned int dst_pitch, const void *sr
>   void drm_fb_xrgb8888_to_rgb888_toio(void __iomem *dst, unsigned int dst_pitch,
>   				    const void *vaddr, const struct drm_framebuffer *fb,
>   				    const struct drm_rect *clip);
> +void drm_fb_xrgb8888_to_xrgb2101010_toio(void __iomem *dst, unsigned int dst_pitch,
> +					 const void *vaddr, const struct drm_framebuffer *fb,
> +					 const struct drm_rect *clip);
>   void drm_fb_xrgb8888_to_gray8(void *dst, unsigned int dst_pitch, const void *vaddr,
>   			      const struct drm_framebuffer *fb, const struct drm_rect *clip);
>   
> 

-- 
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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