Re: [PATCH 2/2] drm/panel: simple: Add timings for Raspberry Pi 7" panel
From: Tomi Valkeinen
Date: Thu Apr 23 2026 - 08:30:18 EST
Hi,
On 23/04/2026 15:14, Maxime Ripard wrote:
Hi,Indeed, it's confusing. I'm a bit new to this so I don't know all the details. From Dave's mail to me about panel-ilitek-ili9881c.c:
On Thu, Apr 23, 2026 at 03:01:51PM +0300, Tomi Valkeinen wrote:
On 22/04/2026 22:22, Dmitry Baryshkov wrote:
On Mon, Apr 20, 2026 at 04:13:36PM +0300, Tomi Valkeinen wrote:
Add timings for the panel used in Raspberry Pi 7" DSI Display module:
https://www.raspberrypi.com/products/raspberry-pi-touch-display/
This has been tested with version v1.1 of the display module.
The panel is very strict about the back-porch values, they must be
exactly 46 for hbp and 23 for vbp. Other timings can be defined quite
freely.
The panel is exclusive to Raspberry Pi, and different versions of the
display module can have panels from different vendors which are fully
compatible. Also, as the panel vendors are not public, the compatible
string used is "raspberrypi,7inch-dsi".
Note that while the display module has a DSI connector, and the
compatible has "dsi" in it, we use DRM_MODE_CONNECTOR_DPI as the panel
itself is a parallel video panel. The display module (as of v1.1) uses
TC358762 DSI-to-DPI bridge to do the conversion.
We could use DRM_MODE_CONNECTOR_DSI here, which would have the benefit
of showing a "DSI-1" connector to the userspace. However, the panel IS a
DPI panel, and gets its input from a DSI-to-DPI bridge, and the
panel-simple.c behaves differently depending on the connector type used,
so, DRM_MODE_CONNECTOR_DPI it is.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/panel/panel-simple.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 91ab280869ba..e75eb20301f2 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -4208,6 +4208,35 @@ static const struct panel_desc rocktech_rk043fn48h = {
.connector_type = DRM_MODE_CONNECTOR_DPI,
};
+static const struct display_timing raspberrypi_7inch_timing = {
+ .pixelclock = { 10000000, 30000000, 50000000 },
+ .hactive = { 800, 800, 800 },
+ .hfront_porch = { 16, 72, 354 },
+ .hsync_len = { 1, 32, 40 },
+ .hback_porch = { 46, 46, 46 },
+ .vactive = { 480, 480, 480 },
+ .vfront_porch = { 7, 21, 147 },
+ .vsync_len = { 1, 2, 20 },
+ .vback_porch = { 23, 23, 23 },
+ .flags = DISPLAY_FLAGS_VSYNC_HIGH | DISPLAY_FLAGS_HSYNC_HIGH,
+ /* Note: the rest of the flags are defined below in bus_flags */
+};
This looks pretty close to powertip panels that have been used before
hand in those modules. Are you sure that powertip,ph800480t013-idf02
or powertip,ph800480t032-zhc19 don't work for you?
I haven't tested those, but the hbp and vbp do not seem to be the same. For
me, they had to be exactly as they are here. This was also confirmed from
Raspberry Pi, the panel datasheet had min/typ/max values (i.e. not ranges)
of 46 and 23 for back porches.
Where did the information come from that powertip,ph800480t013-idf02 or
powertip,ph800480t032-zhc19 are used in the display modules? Or did you mean
that while those models are not used in the Raspberry display module, people
have used them successfully?
It also looks like we have panel-raspberrypi-touchscreen.c and raspberrypi,dsi-7inch in
panel-ilitek-ili9881c.c.
There's clearly more than one "7-inch rpi panel" so clarifying how it
compares to the other two drivers would help.
"
The two variants listed on https://www.raspberrypi.com/products/touch-display-2/
5" and 7" panels, both at 720x1280 (portrait), using the ILI9881
display controller and Goodix GT911 touch controller.
"
So that one is a different line of display modules.
panel-raspberrypi-touchscreen.c: this one is interesting, it's some kind of multi-device driver for the display module, but indeed, it's for the same module that this patch deals with. In my view that multi-device driver is deprecated.
I can clarify these, as per my best understanding, on the patch desc.
Tomi