linux-kernel - [PATCH v2] drivers: qcom: rpmh-rsc: Do not read back the register write on trigger

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Message-Id: <1609230801-31721-1-git-send-email-mkshah@codeaurora.org>
Date:   Tue, 29 Dec 2020 14:03:21 +0530
From:   Maulik Shah <mkshah@...eaurora.org>
To:     bjorn.andersson@...aro.org, agross@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        dianders@...omium.org, ilina@...eaurora.org, lsrao@...eaurora.org,
        Maulik Shah <mkshah@...eaurora.org>
Subject: [PATCH v2] drivers: qcom: rpmh-rsc: Do not read back the register write on trigger

From: Lina Iyer <ilina@...eaurora.org>

When triggering a TCS to send its contents, reading back the trigger
value may return an incorrect value. That is because, writing the
trigger may raise an interrupt which could be handled immediately and
the trigger value could be reset in the interrupt handler.

A write_tcs_reg_sync() would read back the value that is written and try
to match it to the value written to ensure that the value is written,
but if that value is different, we may see false error for same.

Fixes: 658628e7ef78 ("drivers: qcom: rpmh-rsc: add RPMH controller for QCOM SoCs")
Signed-off-by: Lina Iyer <ilina@...eaurora.org>
Signed-off-by: Maulik Shah <mkshah@...eaurora.org>
Reviewed-by: Douglas Anderson <dianders@...omium.org>
---
Changes in v2:
- Add Fixes tag
- Add Reviewed-by tag
---
 drivers/soc/qcom/rpmh-rsc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
index 37969dc..0b082ec 100644
--- a/drivers/soc/qcom/rpmh-rsc.c
+++ b/drivers/soc/qcom/rpmh-rsc.c
@@ -364,7 +364,7 @@ static void __tcs_set_trigger(struct rsc_drv *drv, int tcs_id, bool trigger)
 		enable = TCS_AMC_MODE_ENABLE;
 		write_tcs_reg_sync(drv, RSC_DRV_CONTROL, tcs_id, enable);
 		enable |= TCS_AMC_MODE_TRIGGER;
-		write_tcs_reg_sync(drv, RSC_DRV_CONTROL, tcs_id, enable);
+		write_tcs_reg(drv, RSC_DRV_CONTROL, tcs_id, enable);
 	}
 }
 
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