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Tue, 31 Aug 2021 05:23:45 -0700 (PDT) Date: Tue, 31 Aug 2021 14:23:43 +0200 From: Daniel Vetter To: Noralf =?iso-8859-1?Q?Tr=F8nnes?= Cc: Daniel Vetter , dri-devel@lists.freedesktop.org, peter@stuge.se, linus.walleij@linaro.org, Thomas Zimmermann Subject: Re: [PATCH 2/7] drm/format-helper: Add drm_fb_xrgb8888_to_rgb332() Message-ID: References: <20210817122917.49929-1-noralf@tronnes.org> <20210817122917.49929-3-noralf@tronnes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Operating-System: Linux phenom 5.10.0-8-amd64 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, Aug 30, 2021 at 02:08:14PM +0200, Noralf Trønnes wrote: > > > Den 17.08.2021 15.56, skrev Daniel Vetter: > > On Tue, Aug 17, 2021 at 02:29:12PM +0200, Noralf Trønnes wrote: > >> Add XRGB8888 emulation support for devices that can only do RGB332. > >> > >> Cc: Thomas Zimmermann > >> Signed-off-by: Noralf Trønnes > >> --- > >> drivers/gpu/drm/drm_format_helper.c | 47 +++++++++++++++++++++++++++++ > >> include/drm/drm_format_helper.h | 2 ++ > >> 2 files changed, 49 insertions(+) > >> > >> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c > >> index 5231104b1498..53b426da7467 100644 > >> --- a/drivers/gpu/drm/drm_format_helper.c > >> +++ b/drivers/gpu/drm/drm_format_helper.c > >> @@ -135,6 +135,53 @@ void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb, > >> } > >> EXPORT_SYMBOL(drm_fb_swab); > >> > >> +static void drm_fb_xrgb8888_to_rgb332_line(u8 *dbuf, u32 *sbuf, unsigned int pixels) > >> +{ > >> + unsigned int x; > >> + > >> + for (x = 0; x < pixels; x++) > >> + dbuf[x] = ((sbuf[x] & 0x00e00000) >> 16) | > > > > I think for 2/3 bits correct rounding would be useful, not just masking. > > i.e. before you shift add 0x00100000 here, and similar below. > > > > Math isn't my strongest side and my brain failed to turn this into code. Essentially add half of the lowest bit before you mask, so ((sbuf[x] + 0x10) & 0xe0 ) I dropped the shift to make it clear what's going on. If you're mask is 0xc0, then you simply add 0x20 before masking. > > Also I just realized we've totally ignored endianess on these, which is > > not great, because strictly speaking all the drm_fourcc codes should be > > little endian. But I'm also not sure that's worth fixing ... > > > > Is it as simple as using le32_to_cpu()? I think so. Plus on any format that has u16 output we'd need a cpu_to_le16 wrapped around the entire thing. -Daniel > static void drm_fb_xrgb8888_to_rgb332_line(u8 *dbuf, __le32 *sbuf, > unsigned int pixels) > { > unsigned int x; > u32 pix; > > for (x = 0; x < pixels; x++) { > pix = le32_to_cpu(sbuf[x]); > dbuf[x] = ((pix & 0x00e00000) >> 16) | > ((pix & 0x0000e000) >> 11) | > ((pix & 0x000000c0) >> 6); > } > } > > Noralf. > > > Either way, lgtm: > > > > Reviewed-by: Daniel Vetter > > > >> + ((sbuf[x] & 0x0000e000) >> 11) | > >> + ((sbuf[x] & 0x000000c0) >> 6); > >> +} > >> + > >> +/** > >> + * drm_fb_xrgb8888_to_rgb332 - Convert XRGB8888 to RGB332 clip buffer > >> + * @dst: RGB332 destination buffer > >> + * @src: XRGB8888 source buffer > >> + * @fb: DRM framebuffer > >> + * @clip: Clip rectangle area to copy > >> + * > >> + * Drivers can use this function for RGB332 devices that don't natively support XRGB8888. > >> + * > >> + * This function does not apply clipping on dst, i.e. the destination is a small buffer > >> + * containing the clip rect only. > >> + */ > >> +void drm_fb_xrgb8888_to_rgb332(void *dst, void *src, struct drm_framebuffer *fb, > >> + struct drm_rect *clip) > >> +{ > >> + size_t width = drm_rect_width(clip); > >> + size_t src_len = width * sizeof(u32); > >> + unsigned int y; > >> + void *sbuf; > >> + > >> + /* Use a buffer to speed up access on buffers with uncached read mapping (i.e. WC) */ > >> + sbuf = kmalloc(src_len, GFP_KERNEL); > >> + if (!sbuf) > >> + return; > >> + > >> + src += clip_offset(clip, fb->pitches[0], sizeof(u32)); > >> + for (y = 0; y < drm_rect_height(clip); y++) { > >> + memcpy(sbuf, src, src_len); > >> + drm_fb_xrgb8888_to_rgb332_line(dst, sbuf, width); > >> + src += fb->pitches[0]; > >> + dst += width; > >> + } > >> + > >> + kfree(sbuf); > >> +} > >> +EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb332); > >> + > >> static void drm_fb_xrgb8888_to_rgb565_line(u16 *dbuf, u32 *sbuf, > >> unsigned int pixels, > >> bool swab) > >> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h > >> index 4e0258a61311..d0809aff5cf8 100644 > >> --- a/include/drm/drm_format_helper.h > >> +++ b/include/drm/drm_format_helper.h > >> @@ -16,6 +16,8 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vadd > >> struct drm_rect *clip); > >> void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb, > >> struct drm_rect *clip, bool cached); > >> +void drm_fb_xrgb8888_to_rgb332(void *dst, void *vaddr, struct drm_framebuffer *fb, > >> + struct drm_rect *clip); > >> void drm_fb_xrgb8888_to_rgb565(void *dst, void *vaddr, > >> struct drm_framebuffer *fb, > >> struct drm_rect *clip, bool swab); > >> -- > >> 2.32.0 > >> > > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch