From c4ede56172dc5a9b60d7b7f11a5cf2073b14c14e Mon Sep 17 00:00:00 2001 From: Pavan Holla Date: Tue, 9 Apr 2024 01:58:57 +0000 Subject: [PATCH] usb: typec: ucsi: Wait 20ms before reading CCI after a reset 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 Reviewed-by: Prashant Malani Reviewed-by: Heikki Krogerus Link: https://lore.kernel.org/r/20240409-ucsi-reset-delay-v3-1-8440710b012b@chromium.org Signed-off-by: Greg Kroah-Hartman --- 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 0e37404d309a2..36e1b191f87dc 100644 --- a/drivers/usb/typec/ucsi/ucsi.c +++ b/drivers/usb/typec/ucsi/ucsi.c @@ -1337,6 +1337,9 @@ 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; @@ -1350,7 +1353,6 @@ static int ucsi_reset_ppm(struct ucsi *ucsi) goto out; } - msleep(20); } while (!(cci & UCSI_CCI_RESET_COMPLETE)); out: -- 2.30.2