linux-kernel - Re: [PATCH v3] mhi: host: Add standard elf image download functionality

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Message-ID: <ttpn6o2far7xebghblurxvi43aohv74v7jq2vdgc4jhgc7avo2@lgp4y4sytene>
Date: Sat, 6 Dec 2025 13:25:34 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Qiang Yu <qiang.yu@....qualcomm.com>
Cc: Manivannan Sadhasivam <mani@...nel.org>, mhi@...ts.linux.dev,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Mayank Rana <mayank.rana@....qualcomm.com>,
        Baochen Qiang <quic_bqiang@...cinc.com>
Subject: Re: [PATCH v3] mhi: host: Add standard elf image download
 functionality

On Mon, Dec 01, 2025 at 06:33:15PM -0800, Qiang Yu wrote:
> From: Mayank Rana <mayank.rana@....qualcomm.com>
> 
> Currently, the FBC image is a non-standard ELF file that contains a single
> ELF header, followed by segments for SBL, and WLAN FW. However, TME-L
> (Trust Management Engine Lite) supported devices (eg. QCC2072) requires
> separate ELF headers for SBL and WLAN FW segments due to TME-L image
> authentication requirement.
> 
> Current image format contains two sections in a single binary:
> - First 512KB: ELF header + SBL segments
> - Remaining: WLAN FW segments
> 
> The TME-L supported image format contains two sections with two elf
> headers in a single binary:
> - First 512KB: First ELF header + SBL segments
> - Remaining: Second ELF header + WLAN FW segments
> 
> Download behavior:
> - Legacy: 1. First 512KB via BHI (ELF header + SBL)
>           2. Full image via BHIe
> 
> - TME-L: 1. First 512KB via BHI (First ELF header + SBL)
>          2. Remaining via BHIe (Second ELF header + WLAN FW segments)
> 
> Add standard_elf_image flag to mhi_controller_config to indicate TME-L
> supported image format. When set, MHI skips the first 512KB during WLAN FW
> download over BHIe as it is loaded in BHI phase.

What is standard about it?

> 
> Reviewed-by: Baochen Qiang <quic_bqiang@...cinc.com>
> Signed-off-by: Mayank Rana <mayank.rana@....qualcomm.com>
> Co-developed-by: Qiang Yu <qiang.yu@....qualcomm.com>
> Signed-off-by: Qiang Yu <qiang.yu@....qualcomm.com>
> ---
> Changes in v3:
> - Reword commit message.
> - Reword comments of standard_elf_image flag
> - Add reviewed-by tag.
> - Link to v2: https://lore.kernel.org/mhi/20250603-standard_elf_image_load_support-v2-1-cce97644e99e@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 205d83ac069f15a19ab2d66a63692e5d60334d4c..64fb7a257d3529167eddf1153d34cc6b25735809 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"));
> +		if (mhi_cntrl->standard_elf_image) {
> +			fw_data += mhi_cntrl->sbl_size;
> +			fw_sz -= mhi_cntrl->sbl_size;
> +		}
> +
>  		ret = mhi_alloc_bhie_table(mhi_cntrl, &mhi_cntrl->fbc_image, fw_sz);
>  		if (ret) {
>  			release_firmware(firmware);
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index dd372b0123a6da5107b807ff8fe940c567eb2030..a13106bb234d22e3876dff3c0d46f3dee1d9e05c 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -360,6 +360,9 @@ struct mhi_controller_config {
>   * @bounce_buf: Use of bounce buffer
>   * @fbc_download: MHI host needs to do complete image transfer (optional)
>   * @wake_set: Device wakeup set flag
> + * @standard_elf_image: Flag to determine whether the first 512 KB of the FBC
> + *                      image need to be skipped when loading WLAN FW over
> + *                      BHIe interface (optional)

How does the description correlate to the name of the flag?

>   * @irq_flags: irq flags passed to request_irq (optional)
>   * @mru: the default MRU for the MHI device
>   *
> @@ -445,6 +448,7 @@ struct mhi_controller {
>  	bool bounce_buf;
>  	bool fbc_download;
>  	bool wake_set;
> +	bool standard_elf_image;

This flag is never set, making it a dead API. If there are other patches
setting up the flag, please include them into them in the same series.

>  	unsigned long irq_flags;
>  	u32 mru;
>  };
> 
> ---
> base-commit: ac35e04f8000aaaf98635792464647e7a6f3422e
> change-id: 20251129-wlan_image_load_skip_512k-ddcfe49db8e3
> 
> Best regards,
> -- 
> Qiang Yu <qiang.yu@....qualcomm.com>
> 

-- 
With best wishes
Dmitry