[U-Boot] [PATCH 1/3] efi_loader: correctly determine if an MMC device is an SD-card

[Heinrich Schuchardt <xypron.glpk@gmx.de>]

On 12/04/2017 12:16 AM, Alexander Graf wrote:
> 
> 
> On 02.12.17 13:42, Heinrich Schuchardt wrote:
>> The SD cards and eMMC devices have different device nodes.
>> The current coding interpretes all MMC devices as eMMC.
>>
>> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
>> ---
>>   lib/efi_loader/efi_device_path.c | 24 +++++++++++++++++++++---
>>   1 file changed, 21 insertions(+), 3 deletions(-)
>>
>> diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
>> index b4e2f933cb..42fe6e1185 100644
>> --- a/lib/efi_loader/efi_device_path.c
>> +++ b/lib/efi_loader/efi_device_path.c
>> @@ -36,6 +36,24 @@ static const struct efi_device_path_vendor ROOT = {
>>   	.guid = U_BOOT_GUID,
>>   };
>>   
>> +#if defined(CONFIG_DM_MMC) && defined(CONFIG_MMC)
>> +/*
>> + * Determine if an MMC device is an SD card.
>> + *
>> + * @desc	block device descriptor
>> + * @return	true if the device is an SD card
>> + */
>> +static bool is_sd(struct blk_desc *desc)
>> +{
>> +	struct mmc *mmc = find_mmc_device(desc->devnum);
>> +
>> +	if (!mmc)
>> +		return false;
>> +
>> +	return IS_SD(mmc) != 0U;
>> +}
>> +#endif
>> +
>>   static void *dp_alloc(size_t sz)
>>   {
>>   	void *buf;
>> @@ -298,9 +316,9 @@ static void *dp_fill(void *buf, struct udevice *dev)
>>   		struct blk_desc *desc = mmc_get_blk_desc(mmc);
>>   
>>   		sddp->dp.type     = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
>> -		sddp->dp.sub_type = (desc->if_type == IF_TYPE_MMC) ?
>> -			DEVICE_PATH_SUB_TYPE_MSG_MMC :
>> -			DEVICE_PATH_SUB_TYPE_MSG_SD;
>> +		sddp->dp.sub_type = is_sd(desc) ?
>> +			DEVICE_PATH_SUB_TYPE_MSG_SD :
>> +			DEVICE_PATH_SUB_TYPE_MSG_MMC;
> 
> So in general, MMC != SD != eMMC. Or rather eMMC "is like" SD "is like"
> MMC maybe?
> 
> I really don't know how edk2 distinguishes between them. In general,
> eMMC is an SD card on steroids. Can you double-check in the edk2 code
> and then we just do whatever they do?
> 
> 
> Alex
> 

EDK2 defines the following conversion functions:
   {L"SD",                      DevPathFromTextSd                      },
   {L"eMMC",                    DevPathFromTextEmmc                    },
in MdePkg/Library/UefiDevicePathLib/DevicePathFromText.c:3465
and
   {MESSAGING_DEVICE_PATH, MSG_SD_DP, DevPathToTextSd             },
   {MESSAGING_DEVICE_PATH, MSG_EMMC_DP, DevPathToTextEmmc         },
in MdePkg/Library/UefiDevicePathLib/DevicePathToText.c:2256

Regards

Heinrich