Hi, Haojian JEDEC org doesn't have a eMMC host controller spec. most of eMMC h/c vendors just reuse the SD host controller spec defined by SD Association. Of course there are also some variants on eMMC host controller IP which doesn't follow SD host controller spec perfectly.
The intention of EDKII SD/MMC stack is to cover those HCs/Devices following standard SD/MMC specs. For your Designware case, You would have to have an override version as it doesn't follow SD/MMC specs. Thanks Feng -----Original Message----- From: edk2-devel [mailto:edk2-devel-boun...@lists.01.org] On Behalf Of Haojian Zhuang Sent: Thursday, July 21, 2016 9:40 PM To: Ard Biesheuvel <ard.biesheu...@linaro.org>; Charles Garcia-Tobin <charles.garcia-to...@arm.com> Cc: edk2-devel-01 <edk2-devel@lists.01.org> Subject: Re: [edk2] [PATCH] EmmcBlockIo: fix to get CSD data On 2016/7/21 19:24, Ard Biesheuvel wrote: > On 21 July 2016 at 13:17, Haojian Zhuang <haojian.zhu...@linaro.org> wrote: >> On 2016/7/21 9:52, Haojian Zhuang wrote: >>> >>> >>> 在 07/21/2016 09:51 AM, Haojian Zhuang 写道: >>>> Hi Feng, >>>> >>>> I think the main difference is who to handle the CRC bits. In the >>>> designware emmc/sd controller, the whole 128-bit value is loaded >>>> into the four response registers. There's no any shift on the >>>> 128-bit value to remove CRC. (Refer to: drivers/mmc/host/dw_mmc.c). >>> >>> I mean the implementation in linux. $Linux/drivers/mmc/host/dw_mmc.c >>> >>>> In the eMMC spec, it only mentions R2 response in table. >>>> >>>> Bit position [127:1] >>>> Width (bits) 127 >>>> Value x >>>> Description CID or CSD register incl. >>>> internal CRC7 It also doesn't mention >>>> that we need to shift response value for CSD register. >>>> >>>> So I did this fixing patch. I think that shifting isn't common to >>>> support all eMMC/SD controller IP. Without this patch, the eMMC >>>> stack will only get shifted CSD register value. >>>> It results in parse error. >> >> As I checked the SDHC driver in linux, there's the same logic as you >> implemented in EmmcDxe. >> >> Now the question is whether EmmcDxe is designed for common code of >> all vendor's IP. If so, we need to provide a GetCsd() callback to >> handle different implementations for different vendor. Do you mind >> that I append the GetCsd() callback in EFI_SD_MMC_PASS_THRU_PROTOCOL to fix >> this issue? >> > Unfortunately, you cannot simply add methods to protocols that are > defined by the UEFI spec. If the passthru protocol is lacking in > functionality, we should work with the UEFI forum to get it amended. OK. Maybe we can do the same thing by another way. Now only SDHC needs to shift data for CSD register. We could parse EMMC_CID by EmmcGetCid() in EmmcGetCsd() function. What's your opinion? Best Regards Haojian _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
