Re: [PATCH v2] mhi: host: Add standard elf image download functionality

[Baochen Qiang <quic_bqiang@quicinc.com>]

On 6/6/2025 1:04 AM, Manivannan Sadhasivam wrote:
> On Tue, Jun 03, 2025 at 02:05:44AM -0700, Qiang Yu wrote:
>> From: Mayank Rana <mayank.rana@oss.qualcomm.com>
>>
>> Currently, the FBC image is a non-standard ELF file that contains a single
>> ELF header, followed by segments for SBL, RDDM, and AMSS. Some devices are
>> unable to process this non-standard ELF format and therefore require
>> special handling during image loading.
>>
> 
> What are those "some devices"? Why are they not able to process this format
> which is used across the rest of the Qcom devices?
> 
>> Add standard_elf_image flag to determine whether the device can process
>> the non-standard ELF format. If this flag is set, a standard ELF image
>> must be loaded, meaning the first 512 KB of the FBC image should be
>> skipped when loading the AMSS image over the BHIe interface.
> 
> Please explain what is present in the first 512KiB and why skipping that is
> required.
> 
>> Note that
>> this flag does not affect the SBL image download process.
>>
>> Signed-off-by: Mayank Rana <mayank.rana@oss.qualcomm.com>
>> Co-developed-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
>> Signed-off-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
>> ---
>> Changes in v2:
>> - V1 patch is paused because of no user. WLAN team plan to add support for
>>   new WLAN chip that requires this patch, so send v2.
>> - Change author and SOB with new mail address.
>> - Reword commit message.
>> - Place standard_elf_image flag after wake_set in struct mhi_controller
>> - Link to v1: https://lore.kernel.org/mhi/1689907189-21844-1-git-send-email-quic_qianyu@quicinc.com/
>> ---
>>  drivers/bus/mhi/host/boot.c | 7 +++++++
>>  include/linux/mhi.h         | 4 ++++
>>  2 files changed, 11 insertions(+)
>>
>> diff --git a/drivers/bus/mhi/host/boot.c b/drivers/bus/mhi/host/boot.c
>> index efa3b6dddf4d2f937535243bd8e8ed32109150a4..f1686a8e0681d49f778838820b44f4c845ddbd1f 100644
>> --- a/drivers/bus/mhi/host/boot.c
>> +++ b/drivers/bus/mhi/host/boot.c
>> @@ -584,6 +584,13 @@ void mhi_fw_load_handler(struct mhi_controller *mhi_cntrl)
>>  	 * device transitioning into MHI READY state
>>  	 */
>>  	if (fw_load_type == MHI_FW_LOAD_FBC) {
>> +		dev_dbg(dev, "standard_elf_image:%s\n",
>> +			(mhi_cntrl->standard_elf_image ? "True" : "False"));
> 
> This print is just a noise even for debug.
> 
>> +		if (mhi_cntrl->standard_elf_image) {
>> +			fw_data += mhi_cntrl->sbl_size;
>> +			fw_sz -= mhi_cntrl->sbl_size;
> 
> Is it possible to detect the image type during runtime instead of using a flag?
> Also, the flag is currently unused. So it should come along an user.

The flag would be used when a new WLAN device getting upstream. So either we merge this
patch alone, or we get it grouped within the WLAN patches. Kindly share your thoughts?

> 
> - Mani
>