Messages in this thread | | | Date | Tue, 6 Apr 2010 19:32:11 +0300 | From | Felipe Balbi <> | Subject | Re: [PATCH v3] OMAP: Fix for bus width which improves SD card's peformance. |
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On Tue, Apr 06, 2010 at 06:16:01PM +0200, ext Madhusudhan wrote: > > >> -----Original Message----- >> From: Felipe Balbi [mailto:me@felipebalbi.com] >> Sent: Tuesday, April 06, 2010 12:01 AM >> To: Madhusudhan >> Cc: me@felipebalbi.com; 'kishore kadiyala'; 'Vimal Singh'; >> tony@atomide.com; svenkatr@ti.com; linux-omap@vger.kernel.org; linux- >> kernel@vger.kernel.org; jarkko.lavinen@nokia.com >> Subject: Re: [PATCH v3] OMAP: Fix for bus width which improves SD card's >> peformance. >> >> Hi, >> >> 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.
in that case, the code could be:
WARN_ON(mmc_slot(host).wires > 8);
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;
-- balbi
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