| Message ID | 20240409-ucsi-reset-delay-v3-1-8440710b012b@chromium.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | c4ede56172dc5a9b60d7b7f11a5cf2073b14c14e |
| Headers | show |
| Series | [v3] usb: typec: ucsi: Wait 20ms before reading CCI after a reset | expand |
On Tue, Apr 09, 2024 at 01:58:57AM +0000, Pavan Holla wrote: > The PPM might take time to process a reset. Allow 20ms for the reset to > be processed before reading the CCI. > > This should not slow down existing implementations because they would > not set any bits in the CCI after a reset, and would take a 20ms delay > to read the CCI anyway. This change makes the delay explicit, and > reduces a CCI read. Based on the spec, the PPM has 10ms to set busy, so, > 20ms seems like a reasonable delay before we read the CCI. > > Signed-off-by: Pavan Holla <pholla@chromium.org> > Reviewed-by: Prashant Malani <pmalani@chromium.org> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> > --- > The PPM might take time to process a reset and set the CCI. Give the PPM > 20ms to update it's CCI. > > Commit message now summarizes discussion in v1. > --- > Changes in v3: > - Commit message updated. > - Link to v2: https://lore.kernel.org/r/20240403-ucsi-reset-delay-v2-1-244c175825a4@chromium.org > > Changes in v2: > - Commit message updated. > - Link to v1: https://lore.kernel.org/r/20240325-ucsi-reset-delay-v1-1-d9e183e0f1e6@chromium.org > --- > drivers/usb/typec/ucsi/ucsi.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c > index cf52cb34d285..c0706c40fa64 100644 > --- a/drivers/usb/typec/ucsi/ucsi.c > +++ b/drivers/usb/typec/ucsi/ucsi.c > @@ -1280,6 +1280,9 @@ static int ucsi_reset_ppm(struct ucsi *ucsi) > goto out; > } > > + /* Give the PPM time to process a reset before reading CCI */ > + msleep(20); > + > ret = ucsi->ops->read(ucsi, UCSI_CCI, &cci, sizeof(cci)); > if (ret) > goto out; > @@ -1293,7 +1296,6 @@ static int ucsi_reset_ppm(struct ucsi *ucsi) > goto out; > } > > - msleep(20); > } while (!(cci & UCSI_CCI_RESET_COMPLETE)); > > out: > > --- > base-commit: 4cece764965020c22cff7665b18a012006359095 > change-id: 20240325-ucsi-reset-delay-bdf6712455fd > > Best regards, > -- > Pavan Holla <pholla@chromium.org>
diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c index cf52cb34d285..c0706c40fa64 100644 --- a/drivers/usb/typec/ucsi/ucsi.c +++ b/drivers/usb/typec/ucsi/ucsi.c @@ -1280,6 +1280,9 @@ static int ucsi_reset_ppm(struct ucsi *ucsi) goto out; } + /* Give the PPM time to process a reset before reading CCI */ + msleep(20); + ret = ucsi->ops->read(ucsi, UCSI_CCI, &cci, sizeof(cci)); if (ret) goto out; @@ -1293,7 +1296,6 @@ static int ucsi_reset_ppm(struct ucsi *ucsi) goto out; } - msleep(20); } while (!(cci & UCSI_CCI_RESET_COMPLETE)); out: