Hi Bjorn, Thanks for pulling it into your tree and helping with the verification. On 4/9/2018 5:46 PM, Bjorn Andersson wrote: > On Mon 09 Apr 12:38 PDT 2018, Karthikeyan Ramasubramanian wrote: > >> Add early console support in Qualcomm Technologies Inc., GENI based >> UART controller. >> > > Hi Karthikeyan, > > I pulled this into my SDM845 tree and added "earlycon" to my command > line, the result is a working console up until the serial driver is > probed at which point the console stops. > > > I'm expecting that this should hand over to the normal console as it is > probed, unless I specify keep_bootcon in which case I expect all log > entries to be printed both through the earlycon and the normal console > (i.e. show up twice on the uart). I suspect the issue is something to do with clocks. I will look into it further and fix in the next submission. This is my current hypothesis: When the driver gets probed, it registers the uart port which in turn invokes the console setup. The console setup enables the "se" clock (geni_resources_on()->clk_prepare_enable()). Enabling the "se" clock is disturbing the rate that the clock is already on. Early console write is simultaneously going on while the console is being set up and this clock disturbance is causing the halt. > >> Signed-off-by: Karthikeyan Ramasubramanian <kramasub@xxxxxxxxxxxxxx> >> Signed-off-by: Girish Mahadevan <girishm@xxxxxxxxxxxxxx> > > This is a log of how the patch got to the list (and later to mainline), > as such your name should be the last entry in this line and you should > add an extra Co-Developed-by to indicate that you worked on this > together with Girish. Ok, I will do accordingly. > > Regards, > Bjorn > Regards, Karthik. -- Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
