+linux-mmc On Fri, Apr 15, 2011 at 3:03 PM, Andrei Warkentin <andreiw@xxxxxxxxxxxx> wrote: > On Fri, Apr 15, 2011 at 1:57 PM, Andrei Warkentin <andreiw@xxxxxxxxxxxx> wrote: >> Hi Arindam, >> >> On Fri, Apr 15, 2011 at 12:34 PM, Nath, Arindam <Arindam.Nath@xxxxxxx> wrote: >>> Hi Andrei, >> >>>> >>>> I've recently posted changes relating to CMD23 support in block layer. >>>> Effectively, in order to support hosts with and without Auto-CMD23 >>>> (and with proper error handling) there is a new MMC_CAP_CMD23 for the >>>> host, and a new field "mmc_command sbc" inside the mmc_request. >>>> >>>> I also have a patch enabling CMD23 use with an SDHCI host (< 3.00). >>>> >>>> Could you be so kind as to rebase this patch on top of that? You're >>>> doing a lot of things here that you really shouldn't be (like >>>> enforcing policy on what gets sent to cards, knowing what's connected >>>> to the host, conflicting with reliable writes code if Auto-CMD23 was >>>> enabled for MMCs, not supporting MMCs which always have >>>> SET_BLOCK_COUNT). >>> >>> Our Host Controller is complaint to the Host Controller Spec v3.00, and since Auto CMD23 is a feature added to the HC, I thought it would be better to make this feature part of sdhci and not the core/block layer. >>> >>> But in case you want Auto CMD23 to be implemented in a different way, it would rather be great if you help me implement in your own way, and then probably based on community suggestions, we can keep either of the patch. >> >> Let me clarify: >> >> 1) Sending CMD23 on multiblock transfers is not a an SDHCI specific >> feature. It's a feature of MMC cards and SD cards operating at UHS104 >> or greater. >> 2) CMD23-bounded multi block writes are a generic problem already - >> eMMC reliable writes, for example. >> 3) CMD23 is not bound to any specific controller - so having generic >> code to allow execution of CMD23 will speed up transfers (and enable >> certain features) on any host. >> 4) Auto-CMD is a specific SDHCI enhancement, meant to reduce overhead >> of sending CMD23. >> 5) Host controller has to be aware of CMD23 sending, because on an >> error STOP has to be sent, and without error, no STOP has to be sent. >> >> You are in a unique position where you have functional SDHCI 3.0 >> hardware and are able to test Auto-CMD23. Please look at the patch set >> I sent - it should be trivial to extend current SDHCI patch to use >> Auto-CMD23 when possible instead of sending mmc_request->sbc. >> Basically, I have a generic improvement that affects all host >> controllers. Auto-CMD23 is an optimization of that for SDHCI 3.0. >> >> Your current patch to enable Auto-CMD23 is not useful as far as non-SD >> cards are concerned and you push way to much policy and >> non-host-related complexity into it. >> >> Thanks, >> A >> > > More clarification: > > The block layer patch may change slightly (whitelisting/blacklisting > certain MMC devices for using CMD23 for multiblock transfers), but the > changes to mmc_request and SDHCI are not. So feel free to rebase it > without waiting for anything. If you need help, I will gladly help > you, but keep in mind I don't have SDHCI 3.0 hardware around. > > Thanks, > A > -- 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
