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* [PATCH] spi: spi-geni-qcom: Don't set the cs if it was already right
@ 2020-06-26 22:19 Douglas Anderson
  2020-06-29 11:53 ` Mark Brown
  2020-06-29 19:38 ` Mark Brown
  0 siblings, 2 replies; 4+ messages in thread
From: Douglas Anderson @ 2020-06-26 22:19 UTC (permalink / raw)
  To: Mark Brown
  Cc: linux-arm-msm, swboyd, Dilip Kota, Bjorn Andersson, Andy Gross,
	Douglas Anderson, linux-kernel, linux-spi

Setting the chip select on the Qualcomm geni SPI controller isn't
exactly cheap.  Let's cache the current setting and avoid setting the
chip select if it's already right.

Using "flashrom" to read or write the EC firmware on a Chromebook
shows roughly a 25% reduction in interrupts and a 15% speedup.

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

 drivers/spi/spi-geni-qcom.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c
index 5b1dca1fff79..e99a9d57449f 100644
--- a/drivers/spi/spi-geni-qcom.c
+++ b/drivers/spi/spi-geni-qcom.c
@@ -79,6 +79,7 @@ struct spi_geni_master {
 	unsigned int oversampling;
 	spinlock_t lock;
 	int irq;
+	bool cs_flag;
 };
 
 static int get_spi_clk_cfg(unsigned int speed_hz,
@@ -146,10 +147,15 @@ static void spi_geni_set_cs(struct spi_device *slv, bool set_flag)
 	struct geni_se *se = &mas->se;
 	unsigned long time_left;
 
-	pm_runtime_get_sync(mas->dev);
 	if (!(slv->mode & SPI_CS_HIGH))
 		set_flag = !set_flag;
 
+	if (set_flag == mas->cs_flag)
+		return;
+
+	mas->cs_flag = set_flag;
+
+	pm_runtime_get_sync(mas->dev);
 	spin_lock_irq(&mas->lock);
 	reinit_completion(&mas->cs_done);
 	if (set_flag)
-- 
2.27.0.212.ge8ba1cc988-goog


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] spi: spi-geni-qcom: Don't set the cs if it was already right
  2020-06-26 22:19 [PATCH] spi: spi-geni-qcom: Don't set the cs if it was already right Douglas Anderson
@ 2020-06-29 11:53 ` Mark Brown
  2020-06-29 23:45   ` Doug Anderson
  2020-06-29 19:38 ` Mark Brown
  1 sibling, 1 reply; 4+ messages in thread
From: Mark Brown @ 2020-06-29 11:53 UTC (permalink / raw)
  To: Douglas Anderson
  Cc: linux-arm-msm, swboyd, Dilip Kota, Bjorn Andersson, Andy Gross,
	linux-kernel, linux-spi


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On Fri, Jun 26, 2020 at 03:19:50PM -0700, Douglas Anderson wrote:
> Setting the chip select on the Qualcomm geni SPI controller isn't
> exactly cheap.  Let's cache the current setting and avoid setting the
> chip select if it's already right.

Seems like it'd be worth pushing this up to the core - if we're
constantly setting the same CS value then perhaps we ought to just stop
doing that?

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^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] spi: spi-geni-qcom: Don't set the cs if it was already right
  2020-06-26 22:19 [PATCH] spi: spi-geni-qcom: Don't set the cs if it was already right Douglas Anderson
  2020-06-29 11:53 ` Mark Brown
@ 2020-06-29 19:38 ` Mark Brown
  1 sibling, 0 replies; 4+ messages in thread
From: Mark Brown @ 2020-06-29 19:38 UTC (permalink / raw)
  To: Douglas Anderson
  Cc: Andy Gross, linux-kernel, linux-spi, Dilip Kota, Bjorn Andersson,
	linux-arm-msm, swboyd

On Fri, 26 Jun 2020 15:19:50 -0700, Douglas Anderson wrote:
> Setting the chip select on the Qualcomm geni SPI controller isn't
> exactly cheap.  Let's cache the current setting and avoid setting the
> chip select if it's already right.
> 
> Using "flashrom" to read or write the EC firmware on a Chromebook
> shows roughly a 25% reduction in interrupts and a 15% speedup.

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: spi-geni-qcom: Don't set the cs if it was already right
      commit: 638d8488ae00d2e5dd5033804e82b458d3cf85b1

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH] spi: spi-geni-qcom: Don't set the cs if it was already right
  2020-06-29 11:53 ` Mark Brown
@ 2020-06-29 23:45   ` Doug Anderson
  0 siblings, 0 replies; 4+ messages in thread
From: Doug Anderson @ 2020-06-29 23:45 UTC (permalink / raw)
  To: Mark Brown
  Cc: linux-arm-msm, Stephen Boyd, Dilip Kota, Bjorn Andersson,
	Andy Gross, LKML, linux-spi

Hi,

On Mon, Jun 29, 2020 at 4:53 AM Mark Brown <broonie@kernel.org> wrote:
>
> On Fri, Jun 26, 2020 at 03:19:50PM -0700, Douglas Anderson wrote:
> > Setting the chip select on the Qualcomm geni SPI controller isn't
> > exactly cheap.  Let's cache the current setting and avoid setting the
> > chip select if it's already right.
>
> Seems like it'd be worth pushing this up to the core - if we're
> constantly setting the same CS value then perhaps we ought to just stop
> doing that?

Posted:

spi: Avoid setting the chip select if we don't need to
https://lore.kernel.org/r/20200629164103.1.Ied8e8ad8bbb2df7f947e3bc5ea1c315e041785a2@changeid

I see that you applied my patch to "spi-geni-qcom".  If the patch to
the core looks OK to you and lands, I think the one for the driver can
be reverted (though it doesn't hurt).

-Doug

^ permalink raw reply	[flat|nested] 4+ messages in thread

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Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2020-06-26 22:19 [PATCH] spi: spi-geni-qcom: Don't set the cs if it was already right Douglas Anderson
2020-06-29 11:53 ` Mark Brown
2020-06-29 23:45   ` Doug Anderson
2020-06-29 19:38 ` Mark Brown

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