On Tue, Apr 16, 2024 at 01:45:18PM +0800, Qiang Yu wrote:
>
> On 4/15/2024 7:56 PM, Manivannan Sadhasivam wrote:
> > On Mon, Apr 15, 2024 at 04:49:03PM +0800, Qiang Yu wrote:
> > > Add sysfs entry to allow users of MHI bus force device to enter EDL.
> > > Considering that the way to enter EDL mode varies from device to device and
> > > some devices even do not support EDL. Hence, add a callback edl_trigger in
> > > mhi controller as part of the sysfs entry to be invoked and MHI core will
> > > only create EDL sysfs entry for mhi controller that provides edl_trigger
> > > callback. All of the process a specific device required to enter EDL mode
> > > can be placed in this callback.
> > >
> > > Signed-off-by: Qiang Yu <quic_qianyu@xxxxxxxxxxx>
> > > ---
> > > Documentation/ABI/stable/sysfs-bus-mhi | 11 +++++++++++
> > > drivers/bus/mhi/host/init.c | 35 ++++++++++++++++++++++++++++++++++
> > > include/linux/mhi.h | 2 ++
> > > 3 files changed, 48 insertions(+)
> > >
> > > diff --git a/Documentation/ABI/stable/sysfs-bus-mhi b/Documentation/ABI/stable/sysfs-bus-mhi
> > > index 1a47f9e..d0bf9ae 100644
> > > --- a/Documentation/ABI/stable/sysfs-bus-mhi
> > > +++ b/Documentation/ABI/stable/sysfs-bus-mhi
> > > @@ -29,3 +29,14 @@ Description: Initiates a SoC reset on the MHI controller. A SoC reset is
> > > This can be useful as a method of recovery if the device is
> > > non-responsive, or as a means of loading new firmware as a
> > > system administration task.
> > > +
> > > +What: /sys/bus/mhi/devices/.../force_edl
> > s/force_edl/trigger_edl
> >
> > > +Date: April 2024
> > > +KernelVersion: 6.9
> > > +Contact: mhi@xxxxxxxxxxxxxxx
> > > +Description: Force devices to enter EDL (emergency download) mode. Only MHI
> > How can the user trigger EDL mode? Writing to this file? If so, what is the
> > value?
>
> User can trigger EDL mode by writing a non-zero value to this file.
>
> >
> > 'Emergency Download'
> >
> > > + controller that supports EDL mode and provides a mechanism for
> > > + manually triggering EDL contains this file. Once in EDL mode,
> > 'This entry only exists for devices capable of entering the EDL mode using the
> > standard EDL triggering mechanism defined in the MHI spec <insert the version>.'
> >
> > > + the flash programmer image can be downloaded to the device to
> > > + enter the flash programmer execution environment. This can be
> > > + useful if user wants to update firmware.
> > It'd be good to mention the OS tool like QDL that is used to download firmware
> > over EDL.
>
> OK, can I add an additionnal line like this
> Users: Any OS tools that is used to download firmware over EDL like
> QDL.
>
> >
> > > diff --git a/drivers/bus/mhi/host/init.c b/drivers/bus/mhi/host/init.c
> > > index 44f9349..333ac94 100644
> > > --- a/drivers/bus/mhi/host/init.c
> > > +++ b/drivers/bus/mhi/host/init.c
> > > @@ -127,6 +127,32 @@ static ssize_t soc_reset_store(struct device *dev,
> > > }
> > > static DEVICE_ATTR_WO(soc_reset);
> > > +static ssize_t force_edl_store(struct device *dev,
> > s/force_edl/trigger_edl
> >
> > > + struct device_attribute *attr,
> > > + const char *buf, size_t count)
> > > +{
> > > + struct mhi_device *mhi_dev = to_mhi_device(dev);
> > > + struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
> > > + unsigned long val;
> > > + int ret;
> > > +
> > > + ret = kstrtoul(buf, 10, &val);
> > > + if (ret < 0) {
> > > + dev_err(dev, "Could not parse string: %d\n", ret);
> > No need to print error.
> >
> > > + return ret;
> > > + }
> > > +
> > > + if (!val)
> > > + return count;
> > What does this mean?
>
> If user want to trigger EDL mode,he has to write a non-zero value to this
> file. If he writes zero, nothing will happen.
>
You need to throw -EINVAL for invalid inputs ie., <= 0.
> Do we need to limit the valid value to a specific value like 1?
>
That's not needed.
- Mani
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