Hi Dave, On Sun, Jun 20, 2021 at 03:29:03PM +0100, Dave Stevenson wrote: > On Sun, 20 Jun 2021 at 04:26, Laurent Pinchart wrote: > > > > Hi Maxime, > > > > I'm testing this, and I'm afraid it causes an issue with all the > > I2C-controlled bridges. I'm focussing on the newly merged ti-sn65dsi83 > > driver at the moment, but other are affected the same way. > > > > With this patch, the DSI component is only added when the DSI device is > > attached to the host with mipi_dsi_attach(). In the ti-sn65dsi83 driver, > > this happens in the bridge attach callback, which is called when the > > bridge is attached by a call to drm_bridge_attach() in vc4_dsi_bind(). > > This creates a circular dependency, and the DRM/KMS device is never > > created. > > > > How should this be solved ? Dave, I think you have shown an interest in > > the sn65dsi83 recently, any help would be appreciated. On a side note, > > I've tested the ti-sn65dsi83 driver on a v5.10 RPi kernel, without much > > success (on top of commit e1499baa0b0c I get a very weird frame rate - > > 147 fps of 99 fps instead of 60 fps - and nothing on the screen, and on > > top of the latest v5.10 RPi branch, I get lock-related warnings at every > > page flip), which is why I tried v5.12 and noticed this patch. Is it > > worth trying to bring up the display on the v5.10 RPi kernel in parallel > > to fixing the issue introduced in this patch, or is DSI known to be > > broken there ? > > I've been looking at SN65DSI83/4, but as I don't have any hardware > I've largely been suggesting things to try to those on the forums who > do [1]. > > My branch at https://github.com/6by9/linux/tree/rpi-5.10.y-sn65dsi8x-marek > is the latest one I've worked on. It's rpi-5.10.y with Marek's driver > cherry-picked, and an overlay and simple-panel definition by others. > It also has a rework for vc4_dsi to use pm_runtime, instead of > breaking up the DSI bridge chain (which is flawed as it never calls > the bridge mode_set or mode_valid functions which sn65dsi83 relies > on). > > I ran it on Friday in the lab and encountered an issue with vc4_dsi > should vc4_dsi_encoder_mode_fixup wish for a divider of 7 (required > for this 800x1280 panel over 4 lanes) where it resulted in an invalid > mode configuration. That resulted in patch [2] which then gave me > sensible numbers. > > That branch with dtoverlay=vc4-kms-v3d and > dtoverlay=vc4-kms-dsi-ti-sn65dsi83 created all the expected devices, > and everything came up normally. > It was a busy day, but I think I even stuck a scope on the clock lanes > at that point and confirmed that they were at the link frequency > expected. Thanks, I'll test your branch and will report the results. > Coming back to this patch though, it isn't in 5.10 so I'm not seeing > the issues. As to the exact ordering of attaches, I can't claim > sufficient knowledge on that front. > I can try a cherry-pick of this patch to see what goes on, but it > won't be for a day or two. Let's see if Maxime has an opinion :-) > [1] Largely https://www.raspberrypi.org/forums/viewtopic.php?f=44&t=305690, > but ignore about the first 5 pages of the thread as different driver > versions were floating about. Most stuff after that is based on > Marek's driver. > [2] https://github.com/6by9/linux/commit/c3c774136a1e946109048711d16974be8d520aaa > > > On Tue, Jul 07, 2020 at 12:19:12PM +0200, Maxime Ripard wrote: > > > If the DSI driver is the last to probe, component_add will try to run all > > > the bind callbacks straight away and return the error code. > > > > > > However, since we depend on a power domain, we're pretty much guaranteed to > > > be in that case on the BCM2711, and are just lucky on the previous SoCs > > > since the v3d also depends on that power domain and is further in the probe > > > order. > > > > > > In that case, the DSI host will not stick around in the system: the DSI > > > bind callback will be executed, will not find any DSI device attached and > > > will return EPROBE_DEFER, and we will then remove the DSI host and ask to > > > be probed later on. > > > > > > But since that host doesn't stick around, DSI devices like the RaspberryPi > > > touchscreen whose probe is not linked to the DSI host (unlike the usual DSI > > > devices that will be probed through the call to mipi_dsi_host_register) > > > cannot attach to the DSI host, and we thus end up in a situation where the > > > DSI host cannot probe because the panel hasn't probed yet, and the panel > > > cannot probe because the DSI host hasn't yet. > > > > > > In order to break this cycle, let's wait until there's a DSI device that > > > attaches to the DSI host to register the component and allow to progress > > > further. > > > > > > Suggested-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx> > > > Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx> > > > --- > > > drivers/gpu/drm/vc4/vc4_dsi.c | 25 ++++++++----------------- > > > 1 file changed, 8 insertions(+), 17 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c > > > index eaf276978ee7..19aab4e7e209 100644 > > > --- a/drivers/gpu/drm/vc4/vc4_dsi.c > > > +++ b/drivers/gpu/drm/vc4/vc4_dsi.c > > > @@ -1246,10 +1246,12 @@ static ssize_t vc4_dsi_host_transfer(struct mipi_dsi_host *host, > > > return ret; > > > } > > > > > > +static const struct component_ops vc4_dsi_ops; > > > static int vc4_dsi_host_attach(struct mipi_dsi_host *host, > > > struct mipi_dsi_device *device) > > > { > > > struct vc4_dsi *dsi = host_to_dsi(host); > > > + int ret; > > > > > > dsi->lanes = device->lanes; > > > dsi->channel = device->channel; > > > @@ -1284,6 +1286,12 @@ static int vc4_dsi_host_attach(struct mipi_dsi_host *host, > > > return 0; > > > } > > > > > > + ret = component_add(&dsi->pdev->dev, &vc4_dsi_ops); > > > + if (ret) { > > > + mipi_dsi_host_unregister(&dsi->dsi_host); > > > + return ret; > > > + } > > > + > > > return 0; > > > } > > > > > > @@ -1662,7 +1670,6 @@ static int vc4_dsi_dev_probe(struct platform_device *pdev) > > > { > > > struct device *dev = &pdev->dev; > > > struct vc4_dsi *dsi; > > > - int ret; > > > > > > dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL); > > > if (!dsi) > > > @@ -1670,26 +1677,10 @@ static int vc4_dsi_dev_probe(struct platform_device *pdev) > > > dev_set_drvdata(dev, dsi); > > > > > > dsi->pdev = pdev; > > > - > > > - /* Note, the initialization sequence for DSI and panels is > > > - * tricky. The component bind above won't get past its > > > - * -EPROBE_DEFER until the panel/bridge probes. The > > > - * panel/bridge will return -EPROBE_DEFER until it has a > > > - * mipi_dsi_host to register its device to. So, we register > > > - * the host during pdev probe time, so vc4 as a whole can then > > > - * -EPROBE_DEFER its component bind process until the panel > > > - * successfully attaches. > > > - */ > > > dsi->dsi_host.ops = &vc4_dsi_host_ops; > > > dsi->dsi_host.dev = dev; > > > mipi_dsi_host_register(&dsi->dsi_host); > > > > > > - ret = component_add(&pdev->dev, &vc4_dsi_ops); > > > - if (ret) { > > > - mipi_dsi_host_unregister(&dsi->dsi_host); > > > - return ret; > > > - } > > > - > > > return 0; > > > } > > > -- Regards, Laurent Pinchart
