On Mon, Aug 24, 2020 at 3:17 PM Lukasz Stelmach [off-list ref] wrote:

It was <2020-08-22 sob 14:43>, when Krzysztof Kozlowski wrote:

quoted

On Fri, Aug 21, 2020 at 06:13:59PM +0200, Łukasz Stelmach wrote:

quoted

cur_speed is used to calculate transfer timeout and needs to be
set to the actual value of (half) the clock speed for precise
calculations.

If you need this only for timeout calculation just divide it in
s3c64xx_wait_for_dma().

I divide it here to keep the relationship between the value the variable
holds and the one that is inside clk_* (See? It's multiplied 3 lines
above). If you look around every single clk_get_rate() call in the file is
divided by two.

quoted

Otherwise why only if (cmu) case is updated?

You are righ I will update that too.

However, I wonder if it is even possible that the value read from
S3C64XX_SPI_CLK_CFG would be different than the one written to it?

It is not possible for the register itself, but please see my other
reply, where I explained the integer rounding error which can happen
when calculating the value to write to the register.

quoted

You are also affecting here not only timeout but
s3c64xx_enable_datapath() which is not mentioned in commit log. In other
words, this looks wrong.

Indeed, there is a reference too. I've corrected the message.

Thanks!

Best regards,
Tomasz

quoted

quoted

Cc: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
---
 drivers/spi/spi-s3c64xx.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 02de734b8ab1..89c162efe355 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c

@@ -626,6 +626,7 @@ static int s3c64xx_spi_config(struct s3c64xx_spi_driver_data *sdd)
             ret = clk_set_rate(sdd->src_clk, sdd->cur_speed * 2);
             if (ret)
                     return ret;
+            sdd->cur_speed = clk_get_rate(sdd->src_clk) / 2;
     } else {
             /* Configure Clock */
             val = readl(regs + S3C64XX_SPI_CLK_CFG);
--

2.26.2

--
Łukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel