On Tuesday 13 May 2014 18:13:30 Grant Grundler wrote: > On Wed, May 7, 2014 at 1:35 AM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > > On 7 May 2014 03:52, Nick Sanders <nsanders@xxxxxxxxxxxx> wrote: > >> This patch removes an unneccesary 1ms mdelay in the HS200 tuning > >> loop, called 40 times per retuning. Currently this causes a latency > >> of >40ms on any emmc accesses triggering wake from runtime PM, > >> which can occur for a significant portion of reads on a mostly idle system. > > > > Aha, so you are actually using "MMC_CAP_RUNTIME_RESUME" here - cool :-). > > > > I suppose those patches that enables the "cap" has not reached > > mainline yet. Any plans on sending them? > > > >> > >> The delay is left in place for SD Cards, which use > >> MMC_SEND_TUNING_BLOCK rather than MMC_SEND_TUNING_BLOCK_HS200. > >> I'm not able to find evidence that this is required for SD in the > >> specs I have access to, however this delay has been present from > >> initial checkin for SD so I have preserved the original behavior for > >> compatibility. > >> > >> This has been verified to fix observed glitching on local audio > >> playback and recording on apps with inbuilt assumptions on storage > >> latency. > >> > >> Signed-off-by: Nick Sanders <nsanders@xxxxxxxxxxxx> > >> Reviewed-by: Grant Grundler <grundler@xxxxxxxxxxxx> > >> Reviewed-by: Doug Anderson <dianders@xxxxxxxxxxxx> > > > > Acked-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> > > Ulf, > Is your ACK enough to get this to land upstream or does cjb need to > respond it's been accepted? > > It doesn't appear to have landed in mmc-next branch yet: > http://git.kernel.org/cgit/linux/kernel/git/cjb/mmc.git/log/?h=mmc-next > > apologies if it appears I am being impatient...but it's been almost a week now. > I just stumbled over this thread. Looking at the callers of the execute_tuning() function, I see that all three come from non-atomic context. How about an add-on patch to turn the mdelay(1) into an msleep(1)? That would be much friendlier to other tasks running concurrently. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
