Re: [PATCH 4/5] bus: mhi: host: Update the Time sync logic to read 64 bit register value
From: Konrad Dybcio <hidden>
Date: 2025-09-02 09:14:51
Also in:
linux-arm-msm, lkml
On 8/18/25 8:55 AM, Krishna Chaitanya Chundru wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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