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@xxxxxxxxxxxx> Reviewed-by: Prashant Malani <pmalani@xxxxxxxxxxxx> --- 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@xxxxxxxxxxxx Changes in v2: - Commit message updated. - Link to v1: https://lore.kernel.org/r/20240325-ucsi-reset-delay-v1-1-d9e183e0f1e6@xxxxxxxxxxxx --- 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@xxxxxxxxxxxx>
