linux-kernel - [PATCH v3 07/10] drivers: qcom: rpmh-rsc: tcs_is_free() can just check tcs_in

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Date:   Tue,  7 Apr 2020 16:50:21 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Maulik Shah <mkshah@...eaurora.org>
Cc:     mka@...omium.org, Lina Iyer <ilina@...eaurora.org>,
        Rajendra Nayak <rnayak@...eaurora.org>, swboyd@...omium.org,
        evgreen@...omium.org, Douglas Anderson <dianders@...omium.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 07/10] drivers: qcom: rpmh-rsc: tcs_is_free() can just check tcs_in_use

tcs_is_free() had two checks in it: does the software think that the
TCS is free and does the hardware think that the TCS is free.  I
couldn't figure out in which case the hardware could think that a TCS
was in-use but software thought it was free.  Apparently there is no
case and the extra check can be removed.  This apparently has already
been done in a downstream patch.

Suggested-by: Maulik Shah <mkshah@...eaurora.org>
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---

Changes in v3:
- Replace ("...warn if state mismatch") w/ ("...just check tcs_in_use")

Changes in v2:
- Comment tcs_is_free() new for v2; replaces old patch 6.

 drivers/soc/qcom/rpmh-rsc.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
index 84ae3e514eee..9502e7ea96be 100644
--- a/drivers/soc/qcom/rpmh-rsc.c
+++ b/drivers/soc/qcom/rpmh-rsc.c
@@ -177,7 +177,6 @@ static void write_tcs_reg_sync(struct rsc_drv *drv, int reg, int tcs_id,
  * @tcs_id: The global ID of this TCS.
  *
  * Returns true if nobody has claimed this TCS (by setting tcs_in_use).
- * If the TCS looks free, checks that the hardware agrees.
  *
  * Must be called with the drv->lock held or the tcs_lock for the TCS being
  * tested. If only the tcs_lock is held then it is possible that this
@@ -188,8 +187,7 @@ 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);
+	return !test_bit(tcs_id, drv->tcs_in_use);
 }
 
 /**
-- 
2.26.0.292.g33ef6b2f38-goog