Re: [PATCH V3] scsi: ufs: Get boot device storage type from command line

[Bart Van Assche <bvanassche@acm.org>]

On 7/30/22 00:54, Chetan Chinnadagudihundi Ravindranath (Consultant) 
(QUIC) wrote:
>  > why a change is being made:
> There are 2 variants of the android bootdev device. One is EMMC and 
> other is UFS. We would be not knowing the android boot storage type at 
> build time. So, we need to know the storage type at run time(bootup 
> time) by reading the  "androidboot.bootdevice=". We need to distinguish 
> between EMMC and UFS at bootup time and take appropriate action.
> 
>  > Information about why support is being added for the 
> androidboot.bootdevice parameter in the Qualcomm UFS host controller 
> driver:
> 
> We will get the "androidboot.bootdevice=" by reading cmdline
> case 1: if the boot image header version is 3
>          We get the bootdevice info by reading /proc/cmdline ( 
> __setup("androidboot.bootdevice=", get_android_boot_dev_v3);
> 
> Case 2: if the boot image header version is 4
>          We get the bootdevice info by reading /proc/bootconfig 
> (android_boot_dev_v4 = xbc_find_value("androidboot.bootdevice", &vnode))
> 
> Qualcomm UFS modules(ufs-qcom.c) calls this 
> get_storage_boot_device()(ufs-cmdline.c)   and get the bootdevice info 
> and take appropriate action. This code is yet to be upstreamed. Please 
> let me know if this info convincing.

Instead of posting the above information on the linux-scsi mailing list, 
it should be integrated in the description of the patch. Please do that 
before reposting this patch and also make sure that the code that uses 
this new kernel command line parameter is included in the same patch series.

Thanks,

Bart.