Re: [PATCH] bus: mhi: host: Add sysfs entry to force device to enter EDL

[Qiang Yu]

On 1/3/2024 12:52 AM, Manivannan Sadhasivam wrote:
> On Tue, Jan 02, 2024 at 08:31:15AM -0700, Jeffrey Hugo wrote:
> > On 12/25/2023 12:47 AM, Qiang Yu wrote:
> > > From: Bhaumik Bhatt <quic_bbhatt@xxxxxxxxxxx>
> > >
> > > Forcing the device (eg. SDX75) to enter Emergency Download Mode involves
> > > writing the 0xEDEDEDED cookie to the channel 91 doorbell register and
> > > forcing an SOC reset afterwards. Allow users of the MHI bus to exercise the
> > > sequence using a sysfs entry.
> > I don't see this documented in the spec anywhere.  Is this standard behavior
> > for all MHI devices?
> >
> > What about devices that don't support EDL mode?
> >
> > How should the host avoid using this special cookie when EDL mode is not
> > desired?
> All points raised by Jeff are valid. I had discussions with Hemant and Bhaumik
> previously on allowing the devices to enter EDL mode in a generic manner and we
> didn't conclude on one final approach.
>
> Whatever way we come up with, it should be properly described in the MHI spec
> and _should_ be backwards compatible.

Hi Mani, Jeff. The method of entering EDL mode is documented in MHI spec 
v1.2, Chapter 13.2.

Could you please check once?

> - Mani
>
> > -Jeff