[v2] spi: dw: Fix default polarity of native chipselect

Message ID 20190110212451.12108-1-linus.walleij@linaro.org
State New
Headers show
Series
  • [v2] spi: dw: Fix default polarity of native chipselect
Related show

Commit Message

Linus Walleij Jan. 10, 2019, 9:24 p.m.
The DW controller also supports platforms specifying
native chipselects. When I enforce the use of high CS
for drivers opting in for using GPIO descriptors, I
inadvertedly switched the driver to also use active
high chip select for native chip selects.

As it turns out, the DW hardware driving chip selects
also thinks it is weird with active low chip selects
so all we need to do is remove an inversion in the
driver.

Cc: Janek Kotas <jank@cadence.com>
Reported-by: Janek Kotas <jank@cadence.com>
Fixes: 9400c41e77b8 ("spi: dw: Convert to use CS GPIO descriptors")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

---
ChangeLog v1->v2:
- Missed to alter the actually native chip select
  line control code. I need to be more awake.

Janek can you confirm if this in combination
with the previous patch solves your problem?
---
 drivers/spi/spi-dw.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

-- 
2.19.2

Comments

Linus Walleij Jan. 14, 2019, 1:15 p.m. | #1
On Fri, Jan 11, 2019 at 11:27 AM Janek Kotas <jank@cadence.com> wrote:
> > On 10 Jan 2019, at 22:24, Linus Walleij <linus.walleij@linaro.org> wrote:

> >

> > Janek can you confirm if this in combination

> > with the previous patch solves your problem?

>

> This patch changes the behavior of the DesignWare SPI.

> I don’t use this IP, I can’t test this patch.

>

> The driver I had issues with was the Cadence one, spi-cadence.c.


Sorry for the misunderstanding!

I sent a patch for the cadence driver as well, I will forward
it to you if you can't find it in your inbox.

Yours,
Linus Walleij

Patch

diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index f54b498001a9..64164f1a83f4 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -137,11 +137,10 @@  void dw_spi_set_cs(struct spi_device *spi, bool enable)
 	struct dw_spi *dws = spi_controller_get_devdata(spi->controller);
 	struct chip_data *chip = spi_get_ctldata(spi);
 
-	/* Chip select logic is inverted from spi_set_cs() */
 	if (chip && chip->cs_control)
-		chip->cs_control(!enable);
+		chip->cs_control(enable);
 
-	if (!enable)
+	if (enable)
 		dw_writel(dws, DW_SPI_SER, BIT(spi->chip_select));
 	else if (dws->cs_override)
 		dw_writel(dws, DW_SPI_SER, 0);