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[0/2] serial: qcom-geni: fix opp vote on shutdown

Message ID 20230714130214.14552-1-johan+linaro@kernel.org
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Series serial: qcom-geni: fix opp vote on shutdown | expand

Message

Johan Hovold July 14, 2023, 1:02 p.m. UTC 
This series fixes the missing opp vote removal when closing a serial
port, which, for example, can lead to wasted power when a UART connected
Bluetooth controller is not in use.

Included is also a clean up of a related debug printk.

Johan


Johan Hovold (2):
  serial: qcom-geni: fix opp vote on shutdown
  serial: qcom-geni: clean up clock-rate debug printk

 drivers/tty/serial/qcom_geni_serial.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Comments

Johan Hovold July 14, 2023, 3:08 p.m. UTC | #1 
On Fri, Jul 14, 2023 at 04:29:08PM +0200, Konrad Dybcio wrote:
> On 14.07.2023 15:02, Johan Hovold wrote:
> > The operating-performance-point vote needs to be dropped when shutting
> > down the port to avoid wasting power by keeping resources like power
> > domains in an unnecessarily high performance state (e.g. when a UART
> > connected Bluetooth controller is not in use).
> > 
> > Fixes: a5819b548af0 ("tty: serial: qcom_geni_serial: Use OPP API to set clk/perf state")
> > Cc: stable@vger.kernel.org      # 5.9
> > Cc: Rajendra Nayak <quic_rjendra@quicinc.com>
> > Cc: Matthias Kaehlcke <mka@chromium.org>
> > Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> > ---
> I don't know a whole lot about this subsystem, but the PM call has
> a pointer to uport which already contains this clock rate.. Is it
> zeroed out by the core before we reach it, which would prevent us
> from reusing it?

No, but this driver has other issues and I couldn't be arsed fixing them
before addressing this bug.

Specifically that uartclk variable can currently be set by userspace...

I'll fix that up next week.

Johan
Konrad Dybcio July 15, 2023, 9:19 a.m. UTC | #2 
On 14.07.2023 17:08, Johan Hovold wrote:
> On Fri, Jul 14, 2023 at 04:29:08PM +0200, Konrad Dybcio wrote:
>> On 14.07.2023 15:02, Johan Hovold wrote:
>>> The operating-performance-point vote needs to be dropped when shutting
>>> down the port to avoid wasting power by keeping resources like power
>>> domains in an unnecessarily high performance state (e.g. when a UART
>>> connected Bluetooth controller is not in use).
>>>
>>> Fixes: a5819b548af0 ("tty: serial: qcom_geni_serial: Use OPP API to set clk/perf state")
>>> Cc: stable@vger.kernel.org      # 5.9
>>> Cc: Rajendra Nayak <quic_rjendra@quicinc.com>
>>> Cc: Matthias Kaehlcke <mka@chromium.org>
>>> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
>>> ---
>> I don't know a whole lot about this subsystem, but the PM call has
>> a pointer to uport which already contains this clock rate.. Is it
>> zeroed out by the core before we reach it, which would prevent us
>> from reusing it?
> 
> No, but this driver has other issues and I couldn't be arsed fixing them
> before addressing this bug.
> 
> Specifically that uartclk variable can currently be set by userspace...
> 
> I'll fix that up next week.
OK sounds good

Acked-by: Konrad Dybcio <konrad.dybcio@linaro.org>

Konrad
> 
> Johan