Instead of reading low and high of the mhi registers twice use 64 bit
register value to avoid any time penality.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
---
 drivers/bus/mhi/host/main.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index b7ceeb7261b708d46572d1f68dc277b6e1186b6e..f628198218ef9dc760bbfc3ec496603d1a45dfc1 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -1719,6 +1719,7 @@ static int mhi_get_remote_time(struct mhi_controller *mhi_cntrl, struct mhi_time
 			       struct mhi_timesync_info *time)
 {
 	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	u64 val = U64_MAX;
 	int ret, i;
 
 	if (!mhi_tsync && !mhi_tsync->time_reg) {
@@ -1756,15 +1757,25 @@ static int mhi_get_remote_time(struct mhi_controller *mhi_cntrl, struct mhi_time
 	 * transition to L0.
 	 */
 	for (i = 0; i < MHI_NUM_BACK_TO_BACK_READS; i++) {
-		ret = mhi_read_reg(mhi_cntrl, mhi_tsync->time_reg,
-				   TSC_TIMESYNC_TIME_LOW_OFFSET, &time->t_dev_lo);
+		if (mhi_cntrl->read_reg64) {
+			ret = mhi_read_reg64(mhi_cntrl, mhi_tsync->time_reg,
+					     TSC_TIMESYNC_TIME_LOW_OFFSET, &val);
+		} else {
+			ret = mhi_read_reg(mhi_cntrl, mhi_tsync->time_reg,
+					   TSC_TIMESYNC_TIME_LOW_OFFSET, &time->t_dev_lo);
 
-		ret = mhi_read_reg(mhi_cntrl, mhi_tsync->time_reg,
-				   TSC_TIMESYNC_TIME_HIGH_OFFSET, &time->t_dev_hi);
+			ret = mhi_read_reg(mhi_cntrl, mhi_tsync->time_reg,
+					   TSC_TIMESYNC_TIME_HIGH_OFFSET, &time->t_dev_hi);
+		}
 	}
 
 	time->t_host_post = ktime_get_real();
 
+	if (mhi_cntrl->read_reg64) {
+		time->t_dev_lo = (u32)val;
+		time->t_dev_hi = (u32)(val >> 32);
+	}
+
 	local_irq_enable();
 	preempt_enable();
 

-- 
2.34.1

On 8/18/25 8:55 AM, Krishna Chaitanya Chundru wrote:
> Instead of reading low and high of the mhi registers twice use 64 bit
> register value to avoid any time penality.
> 
> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
> ---
>  drivers/bus/mhi/host/main.c | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
> index b7ceeb7261b708d46572d1f68dc277b6e1186b6e..f628198218ef9dc760bbfc3ec496603d1a45dfc1 100644
> --- a/drivers/bus/mhi/host/main.c
> +++ b/drivers/bus/mhi/host/main.c
> @@ -1719,6 +1719,7 @@ static int mhi_get_remote_time(struct mhi_controller *mhi_cntrl, struct mhi_time
>  			       struct mhi_timesync_info *time)
>  {
>  	struct device *dev = &mhi_cntrl->mhi_dev->dev;
> +	u64 val = U64_MAX;
>  	int ret, i;
>  
>  	if (!mhi_tsync && !mhi_tsync->time_reg) {
> @@ -1756,15 +1757,25 @@ static int mhi_get_remote_time(struct mhi_controller *mhi_cntrl, struct mhi_time
>  	 * transition to L0.
>  	 */
>  	for (i = 0; i < MHI_NUM_BACK_TO_BACK_READS; i++) {
> -		ret = mhi_read_reg(mhi_cntrl, mhi_tsync->time_reg,
> -				   TSC_TIMESYNC_TIME_LOW_OFFSET, &time->t_dev_lo);
> +		if (mhi_cntrl->read_reg64) {
> +			ret = mhi_read_reg64(mhi_cntrl, mhi_tsync->time_reg,
> +					     TSC_TIMESYNC_TIME_LOW_OFFSET, &val);

Since you're passing mhi_cntrl to the read_reg64 function anyway,
perhaps this could remove some verbosity:

int mhi_read_reg64(...) {
	u32 val_hi, val_lo;
	u64 val;

	if (mhi_cntrl->read_reg64) {
		...
	} else {
		...
		val = FIELD_PREP(GENMASK(63, 32), val_hi)) |
		      FIELD_PREP(GENMASK(31, 0), val_lo));
	}

	return val
}


Konrad