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spi: spi-geni-qcom: Don't set the cs if it was already right 

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>
Link: https://lore.kernel.org/r/20200626151946.1.I06134fd669bf91fd387dc6ecfe21d44c202bd412@changeid
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Douglas Anderson 2020-06-26 15:19:50 -07:00 committed by Mark Brown
parent 1ac6f21a94
commit 638d8488ae
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
1 changed files with 7 additions and 1 deletions
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8
drivers/spi/spi-geni-qcom.c
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@ -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)