On Tue, Jun 4, 2019 at 1:14 AM Bean Huo (beanhuo) <bean...@micron.com> wrote:
>
> Hi, Bjorn
>
> >Acquire the device-reset GPIO and toggle this to reset the UFS device during
> >initialization and host reset.
> >
> >+/**
> >+ ufshcd_device_reset() - toggle the (optional) device reset line
> >+ * @hba: per-adapter instance
> >+ *
> >+ * Toggles the (optional) reset line to reset the attached device.
> >+ */
> >+static void ufshcd_device_reset(struct ufs_hba *hba) {
> >+ /*
> >+ * The USB device shall detect reset pulses of 1us, sleep for 10us to
> >+ * be on the safe side.
> >+ */
> >+ gpiod_set_value_cansleep(hba->device_reset, 1);
> >+ usleep_range(10, 15);
> >+
> >+ gpiod_set_value_cansleep(hba->device_reset, 0);
> >+ usleep_range(10, 15);
> >+}
> >+
> > /**
> > * ufshcd_host_reset_and_restore - reset and restore host controller
> > * @hba: per-adapter instance
> >@@ -6159,6 +6179,9 @@ static int ufshcd_reset_and_restore(struct ufs_hba
> >*hba)
> > int retries = MAX_HOST_RESET_RETRIES;
> >
> > do {
> >+ /* Reset the attached device */
> >+ ufshcd_device_reset(hba);
> >+
>
> what's problem you met, and you should reset UFS device here? could you give
> more info?
On the pixel3, devices with micron UFS chips won't boot upstream
kernels without this patch, which is a rewrite of an earlier patch:
https://git.linaro.org/people/john.stultz/android-dev.git/commit/?h=dev/p3&id=99f3dd8519a848b752679584451c45f42c326a17
Which was pulled from the downstream tree from here:
https://android.googlesource.com/kernel/msm.git/+/9c8077087e818017%5E%21/
CCing Subhash as he may have additional context.
thanks
-john
