From: "Noralf Trønnes via B4 Relay" <devnull+noralf.tronnes.org@kernel.org>
To: Neil Armstrong <neil.armstrong@linaro.org>,
Jessica Zhang <quic_jesszhan@quicinc.com>,
Sam Ravnborg <sam@ravnborg.org>,
David Airlie <airlied@gmail.com>,
Daniel Vetter <daniel@ffwll.ch>,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <mripard@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>,
Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Conor Dooley <conor+dt@kernel.org>
Cc: dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
"Kamlesh Gurudasani" <kamlesh.gurudasani@gmail.com>,
"Tommaso Merciai" <tommaso.merciai@amarulasolutions.com>,
"Noralf Trønnes" <noralf@tronnes.org>
Subject: [PATCH 4/5] drm/mipi-dbi: Add support for DRM_FORMAT_RGB888
Date: Tue, 07 May 2024 11:57:29 +0200 [thread overview]
Message-ID: <20240507-panel-mipi-dbi-rgb666-v1-4-6799234afa3e@tronnes.org> (raw)
In-Reply-To: <20240507-panel-mipi-dbi-rgb666-v1-0-6799234afa3e@tronnes.org>
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(-)
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)
*/
--
2.45.0
next prev parent reply other threads:[~2024-05-07 9:57 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-07 9:57 [PATCH 0/5] drm/tiny: panel-mipi-dbi: Support 18 bits per color RGB666 Noralf Trønnes via B4 Relay
2024-05-07 9:57 ` [PATCH 1/5] dt-bindings: display: panel: mipi-dbi-spi: Add a pixel format property Noralf Trønnes via B4 Relay
2024-05-07 20:28 ` Rob Herring
2024-05-07 9:57 ` [PATCH 2/5] drm/mipi-dbi: Remove mipi_dbi_machine_little_endian() Noralf Trønnes via B4 Relay
2024-05-07 9:57 ` [PATCH 3/5] drm/mipi-dbi: Make bits per word configurable for pixel transfers Noralf Trønnes via B4 Relay
2024-05-07 9:57 ` Noralf Trønnes via B4 Relay [this message]
2024-05-07 9:57 ` [PATCH 5/5] drm/tiny: panel-mipi-dbi: Support the pixel format property Noralf Trønnes via B4 Relay
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