On Wed, Oct 30, 2024 at 4:01 AM Frieder Schrempf <[email protected]> wrote: > > Hi Johannes, > > On 25.10.24 10:05 AM, [email protected] wrote: > > [Sie erhalten nicht häufig E-Mails von [email protected]. > > Weitere Informationen, warum dies wichtig ist, finden Sie unter > > https://aka.ms/LearnAboutSenderIdentification ] > > > > Hey, > > We had some problems with the hdmi on the imx8mp and wanted to leave, what > > we found out about it, somewhere for others to find it. > > > > The problem was that our hdmi display sometimes stayed blank after hot > > plugging and sometimes at startup. On older kernel versions 6.6 we did not > > have the problem with the not mainlined hdmi patches. > > We tracked the commit down that introduced the problem for us. It was the > > following “driver core: Enable fw_devlink=rpm by default” > > https://lore.kernel.org/lkml/[email protected]/ > > So we switched back to FW_DEVLINK_FLAGS_ON via kernel parameter. Don’t > > really understand what the problem with RPM is. > > > > So, this information is just for reference. Maybe someone has an idea what > > is going on here. And how to fix the problem in a more proper way. > > Thanks for investigating and sharing your results! > > I'm seeing the same symptoms and previously found out that this is > related to LCDIF underrun errors. See [1] for more information. > > Adam has also started this thread: [2]. > > Anyway, knowing that this is related to fw_devlink=rpm is really > helpful. I just tried with fw_devlink=on and wasn't able to see any > issues anymore. So this confirms your findings.
I was off in the weeds thinking there was something wrong in timing and/or a race condition around the PLL or something. This is good news. Please forgive my ignorance, what does fw_devlink do? Is there something we can do in the driver itself to force its behavior? adam > > I hope that some of the driver framework and runtime PM experts can help > to find out what is actually wrong and how the correct fix might look like. > > I'm also CC-ing Saravana who authored the change from fw_devlink=on to > fw_devlink=rpm to see if they have anything to add. > > Thanks > Frieder > > [1] > https://patchwork.kernel.org/project/linux-phy/cover/[email protected]/#26014057 > [2] > https://lore.kernel.org/imx/[email protected]/T/
