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? Thank you, Chris
