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

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

[Maulik Shah]

From: Lina Iyer <ilina@codeaurora.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.

Signed-off-by: Lina Iyer <ilina@codeaurora.org>
Signed-off-by: Maulik Shah <mkshah@codeaurora.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 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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Re: [PATCH] drivers: qcom: rpmh-rsc: Do not read back the register write on trigger

[Doug Anderson]

Hi,

On Tue, Nov 24, 2020 at 1:53 AM Maulik Shah <mkshah@codeaurora.org> wrote:
>
> From: Lina Iyer <ilina@codeaurora.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.
>
> Signed-off-by: Lina Iyer <ilina@codeaurora.org>
> Signed-off-by: Maulik Shah <mkshah@codeaurora.org>
> ---
>  drivers/soc/qcom/rpmh-rsc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Fixes: 658628e7ef78 ("drivers: qcom: rpmh-rsc: add RPMH controller for
QCOM SoCs")
Signed-off-by: Douglas Anderson <dianders@chromium.org>

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

[Doug Anderson]

Hi,

On Thu, Dec 3, 2020 at 1:15 PM Doug Anderson <dianders@chromium.org> wrote:
>
> Hi,
>
> On Tue, Nov 24, 2020 at 1:53 AM Maulik Shah <mkshah@codeaurora.org> wrote:
> >
> > From: Lina Iyer <ilina@codeaurora.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.
> >
> > Signed-off-by: Lina Iyer <ilina@codeaurora.org>
> > Signed-off-by: Maulik Shah <mkshah@codeaurora.org>
> > ---
> >  drivers/soc/qcom/rpmh-rsc.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
>
> Fixes: 658628e7ef78 ("drivers: qcom: rpmh-rsc: add RPMH controller for
> QCOM SoCs")
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

Ugh, brain-fart.  Not Signed-off-by, but:

Reviewed-by: Douglas Anderson <dianders@chromium.org>

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

[Maulik Shah]

Hi Doug,

On 12/4/2020 2:47 AM, Doug Anderson wrote:
> Hi,
>
> On Thu, Dec 3, 2020 at 1:15 PM Doug Anderson <dianders@chromium.org> wrote:
>> Hi,
>>
>> On Tue, Nov 24, 2020 at 1:53 AM Maulik Shah <mkshah@codeaurora.org> wrote:
>>> From: Lina Iyer <ilina@codeaurora.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.
>>>
>>> Signed-off-by: Lina Iyer <ilina@codeaurora.org>
>>> Signed-off-by: Maulik Shah <mkshah@codeaurora.org>
>>> ---
>>>   drivers/soc/qcom/rpmh-rsc.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>> Fixes: 658628e7ef78 ("drivers: qcom: rpmh-rsc: add RPMH controller for
>> QCOM SoCs")
>> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> Ugh, brain-fart.  Not Signed-off-by, but:
>
> Reviewed-by: Douglas Anderson <dianders@chromium.org>

Thanks for the review, i will send v2 adding Fixes: tag.

Thanks,
Maulik

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