On Fri, Jul 19 2019 at 12:20 -0600, Stephen Boyd wrote:
Quoting Lina Iyer (2019-07-01 08:29:06)
From: "Raju P.L.S.S.S.N" <rplsssn@xxxxxxxxxxxxxx>
tcs->lock was introduced to serialize access with in TCS group. But
even without tcs->lock, drv->lock is serving the same purpose. So
use a single drv->lock.
Isn't the downside now that we're going to be serializing access to the
different TCSes when two are being written in parallel or waited on? I
thought that was the whole point of splitting the lock into a TCS lock
and a general "driver" lock that protects the global driver state vs.
the specific TCS state.
Yes but we were holding the drv->lock as well as tcs->lock for the most
critical of the path anyways (writing to TCS). The added complexity
doesn't seem to help reduce the latency that it expected to reduce.
Other optimizations include -
- Remove locking around clear_bit() in IRQ handler. clear_bit() is
atomic.
- Remove redundant read of TCS registers.
- Use spin_lock instead of _irq variants as the locks are not held
in interrupt context.
Can you please split this patch up into 3 or 4 different patches? I'm
not sure why any of these patches are marked with Fixes either. It's an
optimization patch, not a fix patch, unless the optimization is really
large somehow?
Okay. I will try that.
Fixes: 658628 ("drivers: qcom: rpmh-rsc: add RPMH controller for QCOM
SoCs")
Signed-off-by: Raju P.L.S.S.S.N <rplsssn@xxxxxxxxxxxxxx>
Signed-off-by: Lina Iyer <ilina@xxxxxxxxxxxxxx>
---
drivers/soc/qcom/rpmh-internal.h | 2 --
drivers/soc/qcom/rpmh-rsc.c | 37 +++++++++++---------------------
drivers/soc/qcom/rpmh.c | 20 +++++++----------
3 files changed, 21 insertions(+), 38 deletions(-)
diff --git a/drivers/soc/qcom/rpmh-internal.h b/drivers/soc/qcom/rpmh-internal.h
index a7bbbb67991c..969d5030860e 100644
--- a/drivers/soc/qcom/rpmh-internal.h
+++ b/drivers/soc/qcom/rpmh-internal.h
diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
index e278fc11fe5c..92461311aef3 100644
--- a/drivers/soc/qcom/rpmh-rsc.c
+++ b/drivers/soc/qcom/rpmh-rsc.c
@@ -93,8 +93,7 @@ static void write_tcs_reg_sync(struct rsc_drv *drv, int reg, int tcs_id,
static bool tcs_is_free(struct rsc_drv *drv, int tcs_id)
{
- return !test_bit(tcs_id, drv->tcs_in_use) &&
- read_tcs_reg(drv, RSC_DRV_STATUS, tcs_id, 0);
+ return !test_bit(tcs_id, drv->tcs_in_use);
This can be a diffedjusted rent patch. Why is reading the tcs register
redundant? Please put that information in the commit text.
The tcs_in_use, is adjusted along with the DRV_STS and reading the
tcs_in_use should be enough.
Thanks for your review Stephen.
--Lina
