linux-kernel - Re: [PATCH 2/2] drivers: qcom: rpmh-rsc: fix read back of trigger register

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Message-ID: <20190701155349.GD24030@codeaurora.org>
Date:   Mon, 1 Jul 2019 09:53:49 -0600
From:   Lina Iyer <ilina@...eaurora.org>
To:     agross@...nel.org, bjorn.andersson@...aro.org
Cc:     linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        rnayak@...eaurora.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, swboyd@...omium.org,
        dianders@...omium.org, mkshah@...eaurora.org
Subject: Re: [PATCH 2/2] drivers: qcom: rpmh-rsc: fix read back of trigger
 register

Switching Andy's email address.

On Mon, Jul 01 2019 at 09:32 -0600, Lina Iyer wrote:
>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. By doing a
>read back we may end up spinning waiting for the value we wrote.
>
>Fixes: 658628 ("drivers: qcom: rpmh-rsc: add RPMH controller for QCOM
>SoCs")
>Signed-off-by: Lina Iyer <ilina@...eaurora.org>
>---
> 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 92461311aef3..2fc2fa879480 100644
>--- a/drivers/soc/qcom/rpmh-rsc.c
>+++ b/drivers/soc/qcom/rpmh-rsc.c
>@@ -300,7 +300,7 @@ static void __tcs_trigger(struct rsc_drv *drv, int tcs_id)
> 	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);
> }
>
> static int check_for_req_inflight(struct rsc_drv *drv, struct tcs_group *tcs,
>--
>The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>a Linux Foundation Collaborative Project
>