> -----Original Message----- > From: Nishanth Menon [mailto:nm@xxxxxx] > Sent: Tuesday, April 06, 2010 6:39 PM > To: Chikkature Rajashekar, Madhusudhan > Cc: felipe.balbi@xxxxxxxxx; me@xxxxxxxxxxxxxxx; 'kishore kadiyala'; 'Vimal > Singh'; tony@xxxxxxxxxxx; S, Venkatraman; linux-omap@xxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; 'Lavinen Jarkko (Nokia-D/Helsinki)' > Subject: Re: [PATCH v3] OMAP: Fix for bus width which improves SD card's > peformance. > > Chikkature Rajashekar, Madhusudhan had written, on 04/06/2010 06:23 PM, > the following: > > > >> -----Original Message----- > >> From: Felipe Balbi [mailto:felipe.balbi@xxxxxxxxx] > >> Sent: Tuesday, April 06, 2010 11:57 AM > >> To: ext Nishanth Menon > >> Cc: Balbi Felipe (Nokia-D/Helsinki); Chikkature Rajashekar, > Madhusudhan; > >> me@xxxxxxxxxxxxxxx; 'kishore kadiyala'; 'Vimal Singh'; > tony@xxxxxxxxxxx; > >> S, Venkatraman; linux-omap@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; > >> Lavinen Jarkko (Nokia-D/Helsinki) > >> Subject: Re: [PATCH v3] OMAP: Fix for bus width which improves SD > card's > >> peformance. > >> > >> On Tue, Apr 06, 2010 at 06:55:03PM +0200, ext Nishanth Menon wrote: > >>> some reasons why i love switch statements ;) since I dont expect other > >>> than precisely 4 and 8 (do we expect 5,6,7 - i might be wrong).. but > if > >>> it is so, wont the following be better? > >>> > >>> switch (mmc_slot(host).wires) > >>> { > >>> case 8: > >>> mmc->caps |= MMC_CAP_8_BIT_DATA; > >>> /* fall thru*/ > >>> case 4: > >>> mmc->caps |= MMC_CAP_4_BIT_DATA; > >>> break; > >>> default: > >>> WARN("bad width"); > >>> } > >> I like that, but I remember Madhu (or someone else) saying he thinks > >> it's less readable this way. Go figure... > >> > > Well, I did not comment on the usage of switch here. Note we only need > to > > handle 8-bit and 4-bit.The board files need not setup 8-bit or 4-bit if > the > > configuration of that board is 1-bit. The driver will still work in 1- > bit > > mode which would mean there is nothing to do in default case and should > not > > err out. > check the attachment out.. hope that takes care of it.. just as a > reference alone ofcourse.. Nope. The default case is wrong. The assumption followed by controller drivers is that if the board file says 4-bit or 8-bit set the capabilities otherwise don't do any thing. The host will continue to work in 1-bit mode which is a must. Your patch violates that (can not design a board without connecting one data line at least :)) Also you can not say 1-bit is non-optimal because the board file dictates the configuration based on what it is capable of. Why through a warning? It is subjective. Regards, Madhu > -- > Regards, > Nishanth Menon -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
