RE: [PATCH v3] OMAP: Fix for bus width which improves SD card's peformance.
Date: Tue Apr 06 2010 - 12:16:21 EST
> -----Original Message-----
> From: Felipe Balbi [mailto:me@xxxxxxxxxxxxxxx]
> Sent: Tuesday, April 06, 2010 12:01 AM
> To: Madhusudhan
> Cc: me@xxxxxxxxxxxxxxx; 'kishore kadiyala'; 'Vimal Singh';
> tony@xxxxxxxxxxx; svenkatr@xxxxxx; linux-omap@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; jarkko.lavinen@xxxxxxxxx
> Subject: Re: [PATCH v3] OMAP: Fix for bus width which improves SD card's
> On Mon, Apr 05, 2010 at 12:19:29PM -0500, Madhusudhan wrote:
> > Since the first if command already checks for the 8-bit the second check
> > like >= 4 is definitely not readable in my opinion.
> how come ???
> > Functionally do you see anything wrong with this patch??
> functionally no, but (hypothetical situation) and if on
> omap4/5/6/whatever, omap controller supports a bigger bus width then
> you'll have to add a line like:
> + if (mmc_slot(host).wires == 16)
> + mmc->caps |= (MMC_CAP_16_BIT_DATA | MMC_CAP_8_BIT_DATA |
> + MMC_CAP_4_BIT_DATA);
> - if (mmc_slot(host).wires == 8)
> + else if (mmc_slot(host).wires == 8)
> do you see the problem ?? In my opinion it doesn't scale well.
The point we should note here is that MMC spec supports a max bus width of
8-bit. So anything beyond 8-bit is not in the picture as of today.
But, my bad on miss interpreting the snippet Felipe sent earlier.
if (mmc_slot(host).wires >= 8)
mmc->caps |= MMC_CAP_8_BIT_DATA;
if (mmc_slot(host).wires >= 4)
mmc->caps |= MMC_CAP_4_BIT_DATA;
I missed the fact that you removed the setting of 4-bit from the first
I am okay with the above snippet as it is a trivial change that we are
trying to patch here which fixes an important issue.
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