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

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Message-ID: <z5osod5v6ykmook2cwz76vaww7vnlrh7csx4zebahcaspqr4w5@6an2hopq574o>
Date: Wed, 10 Dec 2025 00:57:11 +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 Sun, Dec 07, 2025 at 10:35:26PM -0800, Qiang Yu wrote:
> On Sat, Dec 06, 2025 at 01:25:34PM +0200, Dmitry Baryshkov wrote:
> > 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?
> 
> The TME-L requires standard elf image format which includes single EFL
> header and WLAN FW segment.
> 
> The "standard_elf_image" seems misleading. Since the new image format is
> required for TME-L image authentication, how about using 
> tme_supported_image?

Just elf_image?

> 
> > 
> > > 
> > > 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?
> 
> The description can be updated as:
> 
>  * @tme_supported_image: Flag indicating FBC image format supports TME-L
>  *                      (Trust Management Engine Lite) authentication.
>  *                      When set, skip first 512KB when loading WLAN FW
>  *                      over BHIe interface (optional)
> > 
> > >   * @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.
> 
> Let me discuss with Baochen about whether he can include the patch in his
> series that actually sets this flag for QCC2072 device.

Otherwise it's a dead API which is generally not allowed.

> 
> - Qiang Yu
> > 
> > >  	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

-- 
With best wishes
Dmitry