Re: [PATCH] tmio_mmc: Revise a limit of the data size

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 25 Aug 2010 22:52:08 +0100
Matt Fleming <matt@console-pimps.org> wrote:

> On Tue, 13 Jul 2010 11:32:33 +0900
> Yusuke Goda <yusuke.goda.sx@renesas.com> wrote:
> 
> > Hi Andrew
> > 
> > Andrew Morton wrote:
> > > On Wed, 07 Jul 2010 11:01:20 +0900
> > > Yusuke Goda <yusuke.goda.sx@renesas.com> wrote:
> > > 
> > >> Signed-off-by: Yusuke Goda <yusuke.goda.sx@renesas.com>
> > >> ---
> > >>  drivers/mmc/host/tmio_mmc.c |    2 +-
> > >>  1 files changed, 1 insertions(+), 1 deletions(-)
> > >>
> > >> diff --git a/drivers/mmc/host/tmio_mmc.c b/drivers/mmc/host/tmio_mmc.c
> > >> index ee7d0a5..cac1c97 100644
> > >> --- a/drivers/mmc/host/tmio_mmc.c
> > >> +++ b/drivers/mmc/host/tmio_mmc.c
> > >> @@ -661,7 +661,7 @@ static int tmio_mmc_start_data(struct tmio_mmc_host *host,
> > >>  		 data->blksz, data->blocks);
> > >>
> > >>  	/* Hardware cannot perform 1 and 2 byte requests in 4 bit mode */
> > >> -	if (data->blksz < 4 && host->mmc->ios.bus_width == MMC_BUS_WIDTH_4) {
> > >> +	if (data->blksz < 2 && host->mmc->ios.bus_width == MMC_BUS_WIDTH_4) {
> > >>  		pr_err("%s: %d byte block unsupported in 4 bit mode\n",
> > >>  		       mmc_hostname(host->mmc), data->blksz);
> > >>  		return -EINVAL;
> > > 
> > > Again, please provide a suitable description for this change.
> > I think the data size is not limited by MMC_BUS_WIDTH_x.
> > I confirmed that data transmission of 2Byte was performed without a problem.
> 
> This patch hasn't been picked up. I'm assuming that's because Andrew is
> still unhappy with the changelog.

Actually I don't know what happened with this.  I merged it on July 8
and appear to have dropped it on July 27, but I can't find its
removed-from-mm email so I don't know why I dropped it.  Weird.

Oh well, I merged it again.  Is 2.6.37 an appropriate merge schedule?

Also, I tend not to handle tmio_mmc patches - usually Paul patches that
driver.

> Andrew, how about something like,
> 
> "When running in 4-bit bus width mode, it is entirely possible to
> transfer data in block sizes of 2 bytes and larger. Relax the
> conditional check to allow 2-byte data block transfers which were
> previously disallowed."

thanks.

> Yusuke, have I interpreted your changelog correctly? Also note that
> your patch should remove the comment above the conditional that says,
> "Hardware cannot perform 1 and 2 byte requests in 4 bit mode".

this?

--- a/drivers/mmc/host/tmio_mmc.c~tmio_mmc-revise-a-limit-of-the-data-size-fix
+++ a/drivers/mmc/host/tmio_mmc.c
@@ -660,7 +660,6 @@ static int tmio_mmc_start_data(struct tm
 	pr_debug("setup data transfer: blocksize %08x  nr_blocks %d\n",
 		 data->blksz, data->blocks);
 
-	/* Hardware cannot perform 1 and 2 byte requests in 4 bit mode */
 	if (data->blksz < 2 && host->mmc->ios.bus_width == MMC_BUS_WIDTH_4) {
 		pr_err("%s: %d byte block unsupported in 4 bit mode\n",
 		       mmc_hostname(host->mmc), data->blksz);
_