From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaehoon Chung Date: Tue, 30 Oct 2012 17:43:56 +0900 Subject: [U-Boot] [PATCH] powerpc/esdhc: force the bus width to 4bit In-Reply-To: <201210231150.49779.marex@denx.de> References: <1350973580-31726-1-git-send-email-Chang-Ming.Huang@freescale.com> <201210230924.28042.marex@denx.de> <110EED8CC96DFC488B7E717A2027A27C1C69C2@039-SN1MPN1-003.039d.mgd.msft.net> <201210231150.49779.marex@denx.de> Message-ID: <508F934C.5020705@samsung.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 10/23/2012 06:50 PM, Marek Vasut wrote: > Dear Huang Changming-R66093, > >> Best Regards >> Jerry Huang >> >>> -----Original Message----- >>> From: Marek Vasut [mailto:marex at denx.de] >>> Sent: Tuesday, October 23, 2012 3:24 PM >>> To: Huang Changming-R66093 >>> Cc: u-boot at lists.denx.de; Andy Fleming >>> Subject: Re: [PATCH] powerpc/esdhc: force the bus width to 4bit >>> >>> Dear Chang-Ming.Huang at freescale.com, >>> >>>> From: Jerry Huang >>>> >>>> For the current u-boot codes, only 4bit/1bit SD/SDHC bus width is >>> >>> support. >>> >>>> So for MMC card, we also support 4bit bus width, otherwiase, we will >>> >>>> get the 12bit bus width, which is not correct: >>> Andy ... can you please explain? I don't quite understand the problem, I >>> thought we had no problem supporting 8bit mmc (esp. if the controller >>> handles that for us mostly). >> >> Yes, the controller support 8bit MMC. >> >> FSL ESDHC driver set the host_caps = MMC_MODE_4BIT | MMC_MODE_8BIT; >> But, the current codes for MMC card has been changed to: >> >> } else { >> width = ((mmc->host_caps & MMC_MODE_MASK_WIDTH_BITS) >> >> MMC_MODE_WIDTH_BITS_SHIFT); >> for (; width >= 0; width--) { >> .... >> >> So for FSL ESDHC, the width = 3, after implement mmc_switch successfully, >> will set the bus to 4 * width. Therefore, I will get the 12bit (4 x 3) bus >> width. This problem is MMC subsystem's bug. I think good that will modify the code in mmc.c. If caps is set to MMC_MODE_4BIT | MMC_MODE_8BIT, we can see the 12bit support with using "mmcinfo" command Best Regards, Jaehoon Chung >> >> Below is the old codes (width = 2): >> } else { >> for (width = EXT_CSD_BUS_WIDTH_8; width >= 0; width--) { > [...] > > > Uh, so it's a bug in the MMC subsystem? > Best regards, > Marek Vasut > _______________________________________________ > U-Boot mailing list > U-Boot at lists.denx.de > http://lists.denx.de/mailman/listinfo/u-boot >