Hi, On Tue, Jun 26, 2018 at 10:27 AM, Rob Clark <robdclark@xxxxxxxxx> wrote: > On Tue, Jun 26, 2018 at 11:55 AM, Doug Anderson <dianders@xxxxxxxxxxxx> wrote: >> Hi, >> >> On Mon, Jun 25, 2018 at 9:45 PM, Sandeep Panda <spanda@xxxxxxxxxxxxxx> wrote: >>> From: Abhinav Kumar <abhinavk@xxxxxxxxxxxxxx> >>> >>> Setting the DSI PLL src in probe doesn't provide the clock >>> driver sufficient time to reclaim unused clock resources >>> from coreboot resulting in warnings from clock driver. >>> >>> Move the DSI PLL src setting to modeset_init() so that the >>> clock driver can claim unused display clock resources before >>> the display driver requests for them again. >> >> IMHO this is a bad design. Sean and Stephen can feel free to override >> me, but I think the clock driver should be improved to handle this >> case and not require the clock to get disabled before Linux enables >> it. >> > > I experimented with it a while back[1] (in this case w/ lk lighting up > the display). In that case I needed both the clk and gdsc code to > realize that clks/gdsc's were on at boot, and fixup the refcnt of the > clks (and parent clocks and so on). And then when probed the display > driver would check if clocks were enabled to decide to readback the > state from the hw. (Maybe you can short-circuit some of that if you > only care about DSI panels with a single fixed resolution, but as soon > as external displays come into the picture you can't assume so much > about the hw state.) > > BR, > -R > > [1] https://github.com/freedreno/kernel-msm/commits/display-handover It seems like something like that is the right real solution here, but I guess someone needs to step up and work on it. ...in general I'm wary of any patch that will not work when "clk_ignore_unused" is passed as a command line parameter. It's useful to be able to use this command line parameter for debugging sometimes and it would be unfortunate if doing so spewed a bunch of extra warnings. On a side node, it appears that even without ${SUBJECT} patch the warnings seem to have gone away with the latest stack of patches I've been testing. The warnings don't even come back with "clk_ignore_unused". I haven't personally dug into why, but I figured I'd mention it. -Doug -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
