Messages in this thread | | | From | "Cai, Cliff" <> | Subject | RE: [PATCH] mmc: align data size for host which only supports power-of-2 block | Date | Wed, 25 Mar 2009 11:22:25 +0800 |
| |
>
>-----Original Message----- >From: Pierre Ossman [mailto:drzeus-mmc@drzeus.cx] >Sent: Sunday, March 15, 2009 4:31 AM >To: Bryan Wu >Cc: linux-kernel@vger.kernel.org; Cai, Cliff; Bryan Wu >Subject: Re: [PATCH] mmc: align data size for host which only >supports power-of-2 block > >On Fri, 6 Mar 2009 11:15:21 +0800 >Bryan Wu <cooloney@kernel.org> wrote: > >> From: Cliff Cai <cliff.cai@analog.com> >> >> Signed-off-by: Cliff Cai <cliff.cai@analog.com> >> Signed-off-by: Bryan Wu <cooloney@kernel.org> >> --- > >This patch seems premature as there is no associated >modification of any of the host drivers.
The SDH on Blackfin BF54x/BF51x only supports power-of-2 block transfer,we will soon Send the sdh driver to mainline as well.
> >> drivers/mmc/core/core.c | 8 +++++++- >> include/linux/mmc/host.h | 1 + >> 2 files changed, 8 insertions(+), 1 deletions(-) >> >> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index >> df6ce4a..15119df 100644 >> --- a/drivers/mmc/core/core.c >> +++ b/drivers/mmc/core/core.c >> @@ -321,7 +321,13 @@ unsigned int mmc_align_data_size(struct >mmc_card *card, unsigned int sz) >> * the core about its problems yet, so for now we just 32-bit >> * align the size. >> */ >> - sz = ((sz + 3) / 4) * 4; >> + >> + /* Align size for host which only supports power-of-2 block */ >> + if (card->host->powerof2_block) { >> + if (sz & (sz - 1)) >> + sz = 1 << fls(sz); >> + } else >> + sz = ((sz + 3) / 4) * 4; >> >> return sz; >> } > >At the very least, the comment at the top of this function >must go. But really, if we want to improve this we should >probably do it properly and have flags for the different >limitations that are available. >Padding to a power of two size can also mean a rather large >padding. We might need to check the host data limits after >doing the adjustment.
Yes,but it's the higher level driver's job.
> >> diff --git a/include/linux/mmc/host.h >b/include/linux/mmc/host.h index >> 4e45725..7416ed1 100644 >> --- a/include/linux/mmc/host.h >> +++ b/include/linux/mmc/host.h >> @@ -162,6 +162,7 @@ struct mmc_host { >> struct dentry *debugfs_root; >> >> unsigned long private[0] ____cacheline_aligned; >> + unsigned int powerof2_block; /* host only >supports power-of-2 block */ >> }; >> >> extern struct mmc_host *mmc_alloc_host(int extra, struct device *); > >This is just broken. Putting it after private completely >breaks accesses to the host driver private data.
Sure,it should be added before private.
Thanks
Cliff
| |