On 2023/12/6 22:56, Dave Stevenson wrote: > Hi Keith > > On Wed, 6 Dec 2023 at 08:55, Keith Zhao <keith.zhao@xxxxxxxxxxxxxxxx> wrote: >> >> >> >> On 2023/11/25 0:04, Dave Stevenson wrote: >> > On Fri, 24 Nov 2023 at 15:00, Stefan Wahren <wahrenst@xxxxxxx> wrote: >> >> >> >> Hi Shengyang, >> >> >> >> [fix address of Emma] >> > >> > Not merged to master yet, but Emma has stepped back from maintenance. >> > https://lists.freedesktop.org/archives/dri-devel/2023-October/428829.html >> > Dropped from the cc. >> > >> >> Am 24.11.23 um 11:44 schrieb Shengyang Chen: >> >> > This patchset adds waveshare 7inch touchscreen panel support >> >> > for the StarFive JH7110 SoC. >> >> > >> >> > Patch 1 add new compatible for the raspberrypi panel driver and its dt-binding. >> >> > Patch 2 add new display mode and new probing process for raspberrypi panel driver. >> >> > >> >> > Waveshare 7inch touchscreen panel is a kind of raspberrypi panel >> >> > which can be drived by raspberrypi panel driver. >> >> > >> >> > The series has been tested on the VisionFive 2 board. >> >> surprisingly i was recently working on the official Raspberry Pi >> >> touchscreen and was able to get it running the new way. >> >> >> >> What do i mean with the new way. There is almost nothing special to the >> >> Raspberry Pi touchscreen, so we should try to use/extend existing >> >> components like: >> >> >> >> CONFIG_DRM_PANEL_SIMPLE >> >> CONFIG_TOUCHSCREEN_EDT_FT5X06 >> >> CONFIG_DRM_TOSHIBA_TC358762 >> >> >> >> The only special part is the Attiny on the connector PCB which requires: >> >> >> >> CONFIG_REGULATOR_RASPBERRYPI_TOUCHSCREEN_ATTINY >> >> >> >> So the whole point is to avoid writing monolitic drivers for simple >> >> panel like that. >> >> >> >> There is a WIP branch based on top of Linux 6.7-rcX, which should >> >> demonstrate this approach [1]. Unfortunately it is not ready for >> >> upstreaming, but it has been tested on a Raspberry Pi 3 B Plus. Maybe >> >> this is helpful for your case. >> >> >> >> Actually i consider panel-raspberrypi-touchscreen.c as a dead end, which >> >> shouldn't be extended. >> > >> > Agreed. >> > >> > The panel control being bound in with the Atmel control has no hook >> > for the EDT5x06 touch driver to hook in and keep the power to the >> > touch controller active. When the panel disable gets called, bye bye >> > touch overlay :-( >> > >> > And I'm reading the driver change as more of a hack to get it to work >> > on your platform, not as adding support for the Waveshare panel >> > variant. >> > Waveshare deliberately cloned the behaviour of the Pi 7" panel in >> > order to make it work with the old Pi firmware drivers, so it >> > shouldn't need any significant changes. Where did the new timings come >> > from? >> > >> > Dave >> hi Dave : >> that's means the panel driver split into 3 sub-modules: >> panel + panel_bridge + regulator. > > Correct. > > You'll have a fourth device in edt_ft5x06 for the touch overlay too, > which will link to the regulator driver for power control. > >> I have a question: in the >> static int rpi_touchscreen_probe(struct i2c_client *i2c) >> { >> ...... >> >> ver = rpi_touchscreen_i2c_read(ts, REG_ID); >> if (ver < 0) { >> dev_err(dev, "Atmel I2C read failed: %d\n", ver); >> return -ENODEV; >> } >> >> switch (ver) { >> case 0xde: /* ver 1 */ >> case 0xc3: /* ver 2 */ >> break; >> default: >> dev_err(dev, "Unknown Atmel firmware revision: 0x%02x\n", ver); >> return -ENODEV; >> } >> >> ...... >> } >> i think this "I2C read" can use to detect whether the panel is connected to dsi controller. >> >> and when split the panel driver into 3 sub-modules, it seems the default way is connected. >> if I drop the panel , run modetest to check the connector status , result connected. >> Is there any way to detect the connection in this case? >> Thanks > > I am not aware of any DSI drivers that support hotplugging, therefore > the connector state will always be connected if the device probes. > > On vc4 the relevant DSI host controller has to have been enabled in > device tree and will be a required component for binding. The DSI host > controller will be waiting on the DSI peripheral driver to call > mipi_dsi_attach, which then calls component_add. If the panel or panel > regulator isn't present, then that never happens if the panel isn't > present, so vc4 won't bind. > It is a little ugly in that you lose the whole DRM card, but that is > how I understand DRM is generally set up to work for DSI or similar > display interfaces. > >> ------------------------------------- >> >> Where did the new timings come from? >> >> ------------------------------------- >> My platform dphy tx hardware has certain limitations. >> Only supports integer multiples of 10M bitrate: >> such as 160M ,170M, 180M,190M,...1G(max) >> >> as common dphy bitrate = pixclock*bpp/lanes. >> This value cannot match successfully in most cases. >> >> so in order to match bitrate , I choose a bitrate value around pixclock*bpp/lanes, >> Prevent overflow and underflow by fine-tuning the timing parameters:-( >> that will make the new timming value. > > That isn't really a function of the panel then. > > All DRM bridges have the option to define a mode_fixup in > drm_bridge_funcs, and that gives you the option to adjust the timings > as required. > > vc4 has a similar constraint in that the PHY only has an integer > divider from a 2 or 3GHz PLL. It implements mode_fixup to compute the > next highest pixel clock, and then adjusts the horizontal front porch > to keep the same line timing. See > https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/vc4/vc4_dsi.c#L825 > I see I never thought that mode fixup is used to do this. This would be a correct way to modify its timming parameters thanks you Dave > Dave > >> > >> >> Btw there are already DT overlays in mainline which seems to use the >> >> Raspberry Pi 7inch panel (without touch function yet) [2]. >> >> >> >> [1] - https://github.com/lategoodbye/rpi-zero/commits/v6.7-7inch-ts >> >> [2] - >> >> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-rpidsi.dtso?h=v6.6.2&id=6b4da1354fd81adace0cda448c77d8f2a47d8474 >> >> >> >> > >> >> > Shengyang Chen (2): >> >> > dt-bindings: display: panel: raspberrypi: Add compatible property for >> >> > waveshare 7inch touchscreen panel >> >> > gpu: drm: panel: raspberrypi: add new display mode and new probing >> >> > process >> >> > >> >> > .../panel/raspberrypi,7inch-touchscreen.yaml | 4 +- >> >> > .../drm/panel/panel-raspberrypi-touchscreen.c | 99 ++++++++++++++++--- >> >> > 2 files changed, 91 insertions(+), 12 deletions(-) >> >> > >> >>
