On 11/19/25 6:24 PM, Chris Morgan wrote: > On Wed, Nov 19, 2025 at 10:02:23AM +0100, Maxime Ripard wrote: >> On Tue, Nov 18, 2025 at 02:36:09PM -0600, Chris Morgan wrote: >>> On Tue, Nov 18, 2025 at 09:46:04AM +0100, Maxime Ripard wrote: >>>> Hi, >>>> >>>> On Thu, Nov 13, 2025 at 01:29:38PM -0600, Chris Morgan wrote: >>>>> From: Chris Morgan <[email protected]> >>>>> >>>>> Add support for the dw-hdmi-qp driver to handle devices with missing >>>>> HPD pins. >>>>> >>>>> Since in this situation we are now polling for the EDID data via i2c >>>>> change the error message to a debug message when we are unable to >>>>> complete an i2c read, as a disconnected device would otherwise fill >>>>> dmesg with i2c read errors. >>>>> >>>>> Signed-off-by: Chris Morgan <[email protected]> >>>> >>>> You must also disable any mode using the scrambler when there's no >>>> hotplug interrupt available. >>> >>> Is there a simple way to do that? I'm not seeing any references to >>> scrambling in the current driver. >>> >>> Should I just limit the rate to HDMI14_MAX_TMDSCLK (340000000) under >>> dw_hdmi_qp_bridge_tmds_char_rate_valid() if using EDID polling? A >>> document I found online from Synopsys [1] claims that scrambling is >>> used by default at rates above 340 (if I'm reading it right) and used >>> opportunistically at rates below 340. >> >> Yep, that's what you should be testing for :) >> >> Maxime > > Thanks, though now that I dig into it I'm a bit more confused on the > best way forward. It looks like for today the driver is hard-limited > to HDMI14_MAX_TMDSCLK because scrambling isn't supported. I'm assuming > it will be at some point, suggesting that we *will* need this in the > future. Is it sufficient to just add a comment there noting we need > to check, or should I add a check there (that does nothing today) > to ensure when we do support faster rates we are ready?
I plan to work on upstreaming the scrambling support soon. Adding a TODO comment would be enough for me to take care of the rest, but I'll still need your help to get that tested, though. :-) Cristian
