From: Douglas Anderson <dianders@chromium.org>
To: Mark Brown <broonie@kernel.org>
Cc: Akash Asthana <akashast@codeaurora.org>,
swboyd@chromium.org, Douglas Anderson <dianders@chromium.org>,
Andy Gross <agross@kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-spi@vger.kernel.org
Subject: [PATCH 1/3] spi: spi-geni-qcom: Use the FIFO even more
Date: Sat, 12 Sep 2020 14:07:59 -0700 [thread overview]
Message-ID: <20200912140730.1.Ie67fa32009b94702d56232c064f1d89065ee8836@changeid> (raw)
In commit 902481a78ee4 ("spi: spi-geni-qcom: Actually use our FIFO") I
explained that the maximum size we could program the FIFO was
"mas->tx_fifo_depth - 3" but that I chose "mas->tx_fifo_depth()"
because I was worried about decreased bandwidth.
Since that time:
* All the interconnect patches have landed, making things run at the
proper speed.
* I've done more measurements.
This lets me confirm that there's really no downside of using the FIFO
more. Specifically I did "flashrom -p ec -r /tmp/foo.bin" on a
Chromebook and averaged over several runs.
Before: It took 6.66 seconds and 59669 interrupts fired.
After: It took 6.66 seconds and 47992 interrupts fired.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---
drivers/spi/spi-geni-qcom.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c
index 0dc3f4c55b0b..7f0bf0dec466 100644
--- a/drivers/spi/spi-geni-qcom.c
+++ b/drivers/spi/spi-geni-qcom.c
@@ -308,7 +308,7 @@ static int spi_geni_init(struct spi_geni_master *mas)
* Hardware programming guide suggests to configure
* RX FIFO RFR level to fifo_depth-2.
*/
- geni_se_init(se, mas->tx_fifo_depth / 2, mas->tx_fifo_depth - 2);
+ geni_se_init(se, mas->tx_fifo_depth - 3, mas->tx_fifo_depth - 2);
/* Transmit an entire FIFO worth of data per IRQ */
mas->tx_wm = 1;
ver = geni_se_get_qup_hw_version(se);
--
2.28.0.618.gf4bc123cb7-goog
next reply other threads:[~2020-09-12 21:08 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-12 21:07 Douglas Anderson [this message]
2020-09-12 21:08 ` [PATCH 2/3] spi: spi-geni-qcom: Don't program CS_TOGGLE again and again Douglas Anderson
2020-09-12 23:01 ` Bjorn Andersson
2020-09-15 10:40 ` Akash Asthana
2020-09-12 21:08 ` [PATCH 3/3] spi: spi-geni-qcom: Slightly optimize setup of bidirectional xfters Douglas Anderson
2020-09-12 22:54 ` Bjorn Andersson
2020-09-13 1:09 ` Doug Anderson
2020-09-13 20:35 ` Doug Anderson
2020-09-13 3:45 ` kernel test robot
2020-09-13 7:31 ` kernel test robot
2020-09-12 22:53 ` [PATCH 1/3] spi: spi-geni-qcom: Use the FIFO even more Bjorn Andersson
2020-09-13 1:11 ` Doug Anderson
2020-09-13 3:12 ` Bjorn Andersson
2020-09-14 14:52 ` Mark Brown
2020-09-15 7:30 ` Akash Asthana
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