On 13/01/15 13:25, Ulf Hansson wrote: > Hi Adrian, > > Thanks for working on this and apologize for my late reply! > > On 5 December 2014 at 18:41, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote: >> Currently, there is core support for tuning during >> initialization. There can also be a need to re-tune >> periodically (e.g. sdhci) or to re-tune after the >> host controller is powered off (e.g. after PM >> runtime suspend / resume) or to re-tune in response >> to CRC errors. >> >> The main requirements for re-tuning are: >> - ability to enable /disable re-tuning >> - ability to flag that re-tuning is needed >> - ability to re-tune before any request >> - ability to hold off re-tuning if the card is busy >> - ability to hold off re-tuning if re-tuning is in >> progress >> - ability to run a re-tuning timer > > I suggest we skip the support for the re-tuning timer in this initial > step and thus remove the related functionality from this patchset. It > adds complexity, but more important it's not obvious that it actually > will help. I am more concerned that it randomly will cause a request > latency and thus decrease performance. > > The re-tuning period can't be selected "perfectly", so in this initial > step let's instead just rely on re-tune from the request retry path. > > If we do see a need for a doing re-tuning periodically, how about > using the runtime PM suspend path (of the mmc card device). In that > way, we should be able to minimize the impact on performance. Thank you for looking at the patches. I am not sure I know what you mean. sdhci already has a re-tuning timer, so this is just moving it into core, where it won't be used by other drivers unless they enable it. I am not sure what you want to leave in sdhci.c and what you want in core, if anything. At a minimum I need sdhci to be able to switch from hs400 to hs200, re-tune, and switch back. -- 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
