| Message ID | 20240603-panel-mipi-dbi-rgb666-v3-4-59ed53ca73da@tronnes.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/tiny: panel-mipi-dbi: Support 18 bits per color RGB666 | expand |
On Mon, Jun 03, 2024 at 01:21:35PM +0200, Noralf Trønnes via B4 Relay wrote: > From: Noralf Trønnes <noralf@tronnes.org> > > DRM_FORMAT_RGB888 is 24 bits per pixel and it would be natural to send it > on the SPI bus using a 24 bits per word transfer. The problem with this > is that not all SPI controllers support 24 bpw. > > Since DRM_FORMAT_RGB888 is stored in memory as little endian and the SPI > bus is big endian we use 8 bpw to always get the same pixel format on the > bus: b8g8r8. > > The MIPI DCS specification lists the standard commands that can be sent > over the MIPI DBI interface. The set_address_mode (36h) command has one > bit in the parameter that controls RGB/BGR order. This means that the > controller can be configured to receive the pixel as BGR. > > RGB888 is rarely supported on these controllers but RGB666 is very common. > All datasheets I have seen do at least support the pixel format option > where each color is sent as one byte and the 6 MSB's are used. > > All this put together means that we can send each pixel as b8g8r8 and an > RGB666 capable controller sees this as b6x2g6x2r6x2. > > Signed-off-by: Noralf Trønnes <noralf@tronnes.org> > --- > drivers/gpu/drm/drm_mipi_dbi.c | 29 +++++++++++++++++++++++++---- > include/drm/drm_mipi_dbi.h | 5 +++++ > 2 files changed, 30 insertions(+), 4 deletions(-) The patch generally LGTM. The only nit is the name of 'emulation_format'. My first impression was that it is a format that the driver is emulating to userspace, however it looks like this is over-the-wire format (with the RGB666 vs RGB888 note kept in mind). If my understanding is correct, I'd suggest renaming emulation_format to something like 'raw_format' or 'panel_format'. > > diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c > index 77f8a828d6e0..eb330676857c 100644 > --- a/drivers/gpu/drm/drm_mipi_dbi.c > +++ b/drivers/gpu/drm/drm_mipi_dbi.c > @@ -206,6 +206,7 @@ int mipi_dbi_buf_copy(void *dst, struct iosys_map *src, struct drm_framebuffer * > struct drm_rect *clip, bool swap, > struct drm_format_conv_state *fmtcnv_state) > { > + struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(fb->dev); > struct drm_gem_object *gem = drm_gem_fb_get_obj(fb, 0); > struct iosys_map dst_map = IOSYS_MAP_INIT_VADDR(dst); > int ret; > @@ -222,8 +223,18 @@ int mipi_dbi_buf_copy(void *dst, struct iosys_map *src, struct drm_framebuffer * > else > drm_fb_memcpy(&dst_map, NULL, src, fb, clip); > break; > + case DRM_FORMAT_RGB888: > + drm_fb_memcpy(&dst_map, NULL, src, fb, clip); > + break; > case DRM_FORMAT_XRGB8888: > - drm_fb_xrgb8888_to_rgb565(&dst_map, NULL, src, fb, clip, fmtcnv_state, swap); > + switch (dbidev->emulation_format) { > + case DRM_FORMAT_RGB565: > + drm_fb_xrgb8888_to_rgb565(&dst_map, NULL, src, fb, clip, fmtcnv_state, swap); > + break; > + case DRM_FORMAT_RGB888: > + drm_fb_xrgb8888_to_rgb888(&dst_map, NULL, src, fb, clip, fmtcnv_state); > + break; > + } > break; > default: > drm_err_once(fb->dev, "Format is not supported: %p4cc\n", [skipped] > diff --git a/include/drm/drm_mipi_dbi.h b/include/drm/drm_mipi_dbi.h > index b36596efdcc3..85bf19b98cee 100644 > --- a/include/drm/drm_mipi_dbi.h > +++ b/include/drm/drm_mipi_dbi.h > @@ -101,6 +101,11 @@ struct mipi_dbi_dev { > */ > struct drm_display_mode mode; > > + /** > + * @emulation_format: Pixel format to use when emulating XRGB8888 > + */ > + u32 emulation_format; > + > /** > * @tx_buf: Buffer used for transfer (copy clip rect area) > */ > > -- > 2.45.1 > >
diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c index 77f8a828d6e0..eb330676857c 100644 --- a/drivers/gpu/drm/drm_mipi_dbi.c +++ b/drivers/gpu/drm/drm_mipi_dbi.c @@ -206,6 +206,7 @@ int mipi_dbi_buf_copy(void *dst, struct iosys_map *src, struct drm_framebuffer * struct drm_rect *clip, bool swap, struct drm_format_conv_state *fmtcnv_state) { + struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(fb->dev); struct drm_gem_object *gem = drm_gem_fb_get_obj(fb, 0); struct iosys_map dst_map = IOSYS_MAP_INIT_VADDR(dst); int ret; @@ -222,8 +223,18 @@ int mipi_dbi_buf_copy(void *dst, struct iosys_map *src, struct drm_framebuffer * else drm_fb_memcpy(&dst_map, NULL, src, fb, clip); break; + case DRM_FORMAT_RGB888: + drm_fb_memcpy(&dst_map, NULL, src, fb, clip); + break; case DRM_FORMAT_XRGB8888: - drm_fb_xrgb8888_to_rgb565(&dst_map, NULL, src, fb, clip, fmtcnv_state, swap); + switch (dbidev->emulation_format) { + case DRM_FORMAT_RGB565: + drm_fb_xrgb8888_to_rgb565(&dst_map, NULL, src, fb, clip, fmtcnv_state, swap); + break; + case DRM_FORMAT_RGB888: + drm_fb_xrgb8888_to_rgb888(&dst_map, NULL, src, fb, clip, fmtcnv_state); + break; + } break; default: drm_err_once(fb->dev, "Format is not supported: %p4cc\n", @@ -260,9 +271,11 @@ static void mipi_dbi_fb_dirty(struct iosys_map *src, struct drm_framebuffer *fb, struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(fb->dev); unsigned int height = rect->y2 - rect->y1; unsigned int width = rect->x2 - rect->x1; + const struct drm_format_info *dst_format; struct mipi_dbi *dbi = &dbidev->dbi; bool swap = dbi->swap_bytes; int ret = 0; + size_t len; bool full; void *tr; @@ -283,8 +296,13 @@ static void mipi_dbi_fb_dirty(struct iosys_map *src, struct drm_framebuffer *fb, mipi_dbi_set_window_address(dbidev, rect->x1, rect->x2 - 1, rect->y1, rect->y2 - 1); - ret = mipi_dbi_command_buf(dbi, MIPI_DCS_WRITE_MEMORY_START, tr, - width * height * 2); + if (fb->format->format == DRM_FORMAT_XRGB8888) + dst_format = drm_format_info(dbidev->emulation_format); + else + dst_format = fb->format; + len = drm_format_info_min_pitch(dst_format, 0, width) * height; + + ret = mipi_dbi_command_buf(dbi, MIPI_DCS_WRITE_MEMORY_START, tr, len); err_msg: if (ret) drm_err_once(fb->dev, "Failed to update display %d\n", ret); @@ -572,7 +590,7 @@ static const uint32_t mipi_dbi_formats[] = { * has one fixed &drm_display_mode which is rotated according to @rotation. * This mode is used to set the mode config min/max width/height properties. * - * Use mipi_dbi_dev_init() if you don't need custom formats. + * Use mipi_dbi_dev_init() if you want native RGB565 and emulated XRGB8888 format. * * Note: * Some of the helper functions expects RGB565 to be the default format and the @@ -631,6 +649,9 @@ int mipi_dbi_dev_init_with_formats(struct mipi_dbi_dev *dbidev, drm->mode_config.min_height = dbidev->mode.vdisplay; drm->mode_config.max_height = dbidev->mode.vdisplay; dbidev->rotation = rotation; + dbidev->emulation_format = formats[0]; + if (formats[0] == DRM_FORMAT_RGB888) + dbidev->dbi.write_memory_bpw = 8; DRM_DEBUG_KMS("rotation = %u\n", rotation); diff --git a/include/drm/drm_mipi_dbi.h b/include/drm/drm_mipi_dbi.h index b36596efdcc3..85bf19b98cee 100644 --- a/include/drm/drm_mipi_dbi.h +++ b/include/drm/drm_mipi_dbi.h @@ -101,6 +101,11 @@ struct mipi_dbi_dev { */ struct drm_display_mode mode; + /** + * @emulation_format: Pixel format to use when emulating XRGB8888 + */ + u32 emulation_format; + /** * @tx_buf: Buffer used for transfer (copy clip rect area) */