> -----Original Message----- > From: Subhash Jadavani [mailto:subhashj@xxxxxxxxxxxxxx] > Sent: Saturday, April 16, 2011 12:07 PM > To: Nath, Arindam; 'Andrei Warkentin'; linux-mmc@xxxxxxxxxxxxxxx > Subject: RE: [PATCH v3 01/12] mmc: sdhci: add support for auto CMD23 > > > > > -----Original Message----- > > From: Nath, Arindam [mailto:Arindam.Nath@xxxxxxx] > > Sent: Saturday, April 16, 2011 11:56 AM > > To: Subhash Jadavani; 'Andrei Warkentin'; linux-mmc@xxxxxxxxxxxxxxx > > Subject: RE: [PATCH v3 01/12] mmc: sdhci: add support for auto CMD23 > > > > Hi Subhash, > > > > > > > -----Original Message----- > > > From: Subhash Jadavani [mailto:subhashj@xxxxxxxxxxxxxx] > > > Sent: Saturday, April 16, 2011 11:47 AM > > > To: 'Andrei Warkentin'; Nath, Arindam; linux-mmc@xxxxxxxxxxxxxxx > > > Subject: RE: [PATCH v3 01/12] mmc: sdhci: add support for auto > CMD23 > > > > > > > -----Original Message----- > > > > From: linux-mmc-owner@xxxxxxxxxxxxxxx [mailto:linux-mmc- > > > > owner@xxxxxxxxxxxxxxx] On Behalf Of Andrei Warkentin > > > > Sent: Saturday, April 16, 2011 1:34 AM > > > > To: Nath, Arindam; linux-mmc@xxxxxxxxxxxxxxx > > > > Subject: Re: [PATCH v3 01/12] mmc: sdhci: add support for auto > > CMD23 > > > > > > > > +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. > > > > > > These are the same point I had discussed earlier with Arindam. > Please > > > check the attached mails. > > > > > > Yes, I would also agree with Andrei that all generic code related > to > > > CMD23 handling should be in core/block layer. Internally host > > > controller driver can handle CMD23 differently as not all host > > > controller support AUTO-CMD23. > > > > Please keep in mind that my patch _only_ adds support for Auto CMD23, > > and not CMD23. CMD23 support can be made part of block layer, but > Auto > > CMD23 is a feature as per the Host Controller Spec v3.00. So my patch > > takes care of the second case. > > Agreed. But point is that Host controller driver should not be sending > CMD23 > to card unless indicated by core/block layer to do so. In your patch > you are > checking in host controller driver that SD card supports CMD23 or not > and > then sending the CMD23 for multi block read/write. MMC cards also > supports > CMD23 so in that case again you have to check MMC EXT_CSD register for > CMD23 Yes, you are right. I followed the Physical Layer Spec v3.01 as is, so in case the support is needed for MMC cards, we will need to take care of that too. > support. All this logic is better be in core/block layer and let > core/block > layer inform host controller when to send CMD23 and when not to. Well in that case, Auto CMD23 will never make sense. Thanks, Arindam > > > > > Thanks, > > Arindam > > > > > > > > > >> 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 > > -- 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
