[PATCH] omap2_mcspi.c: Clock divider range check wrong for OMAP3

[PATCH] omap2_mcspi.c: Clock divider range check wrong for OMAP3

[Scott Ellis]

The clock divider range check is wrong for the OMAP3.

The MCSPI_CHxCONF.CLKD register field has a max value 0x0C 
not 0x0F. Reference was the OMAP3 TRM Rev. D manual.

I don't know whether the old value was correct for OMAP24xxx 
boards so I put in some #ifdef stuff. Maybe someone with access
to the OMAP24xxx manual could check if that is necessary.


Signed-off-by: Scott Ellis <scott@jumpnowtek.com>


 drivers/spi/omap2_mcspi.c |   24 +++++++++++++++++-------
 1 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
index fe1b56d..a73127b 100644
--- a/drivers/spi/omap2_mcspi.c
+++ b/drivers/spi/omap2_mcspi.c
@@ -38,8 +38,17 @@
 #include <plat/dma.h>
 #include <plat/clock.h>
 
+#if defined(CONFIG_ARCH_OMAP3) || defined(CONFIG_ARCH_OMAP4)
+#define OMAP2_MCSPI_MAX_CLK_DIV                12
+#else
+/* could be 12 for OMAP24xxx also, no docs to check */
+#define OMAP2_MCSPI_MAX_CLK_DIV                15
+#endif
 
 #define OMAP2_MCSPI_MAX_FREQ           48000000
+#define OMAP2_MCSPI_MIN_FREQ   (OMAP2_MCSPI_MAX_FREQ \
+                                       / (1 << OMAP2_MCSPI_MAX_CLK_DIV))
+
 
 /* OMAP2 has 3 SPI controllers, while OMAP3 has 4 */
 #define OMAP2_MCSPI_MAX_CTRL           4
@@ -588,11 +597,12 @@ static int omap2_mcspi_setup_transfer(struct spi_device *spi,
        cs->word_len = word_len;
 
        if (spi->max_speed_hz) {
-               while (div <= 15 && (OMAP2_MCSPI_MAX_FREQ / (1 << div))
-                                       > spi->max_speed_hz)
+               while (div <= OMAP2_MCSPI_MAX_CLK_DIV && 
+                       (OMAP2_MCSPI_MAX_FREQ / (1 << div)) > spi->max_speed_hz)
                        div++;
-       } else
-               div = 15;
+       } else {
+               div = OMAP2_MCSPI_MAX_CLK_DIV;
+       }
 
        l = mcspi_cached_chconf0(spi);
 
@@ -917,10 +927,10 @@ static int omap2_mcspi_transfer(struct spi_device *spi, struct spi_message *m)
                                        t->bits_per_word);
                        return -EINVAL;
                }
-               if (t->speed_hz && t->speed_hz < OMAP2_MCSPI_MAX_FREQ/(1<<16)) {
-                       dev_dbg(&spi->dev, "%d Hz max exceeds %d\n",
+               if (t->speed_hz && t->speed_hz < OMAP2_MCSPI_MIN_FREQ) {
+                       dev_dbg(&spi->dev, "%d Hz slower then hardware minimum %d\n",
                                        t->speed_hz,
-                                       OMAP2_MCSPI_MAX_FREQ/(1<<16));
+                                       OMAP2_MCSPI_MIN_FREQ);
                        return -EINVAL;
                }

RE: [PATCH] omap2_mcspi.c: Clock divider range check wrong for OMAP3

[Gadiyar, Anand]

Scott Ellis wrote:
> 
> The clock divider range check is wrong for the OMAP3.
> 
> The MCSPI_CHxCONF.CLKD register field has a max value 0x0C 
> not 0x0F. Reference was the OMAP3 TRM Rev. D manual.
> 
> I don't know whether the old value was correct for OMAP24xxx 
> boards so I put in some #ifdef stuff. Maybe someone with access
> to the OMAP24xxx manual could check if that is necessary.
> 
> 
> Signed-off-by: Scott Ellis <scott@jumpnowtek.com>


I took a look at current 34xx TRM (Rev Z) and 2430 TRM
(Rev Z again). You're right in that the 3430 has a max
value of 0x0C for this field.

The 2430 TRM says 0x0F is valid for the corresponding
field there.

Not really sure what is the correct value, but at least
the documentation says you're right.

Hope this helps.

- Anand

Re: [PATCH] omap2_mcspi.c: Clock divider range check wrong for OMAP3

[Felipe Balbi]

On Mon, Mar 08, 2010 at 06:56:51AM -0500, Scott Ellis wrote:
> diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
> index fe1b56d..a73127b 100644
> --- a/drivers/spi/omap2_mcspi.c
> +++ b/drivers/spi/omap2_mcspi.c
> @@ -38,8 +38,17 @@
>  #include <plat/dma.h>
>  #include <plat/clock.h>
>  
> +#if defined(CONFIG_ARCH_OMAP3) || defined(CONFIG_ARCH_OMAP4)
> +#define OMAP2_MCSPI_MAX_CLK_DIV                12
> +#else
> +/* could be 12 for OMAP24xxx also, no docs to check */
> +#define OMAP2_MCSPI_MAX_CLK_DIV                15
> +#endif
>  
>  #define OMAP2_MCSPI_MAX_FREQ           48000000
> +#define OMAP2_MCSPI_MIN_FREQ   (OMAP2_MCSPI_MAX_FREQ \
> +                                       / (1 << OMAP2_MCSPI_MAX_CLK_DIV))

please don't break multi-omap builds. Pass this constant using platform_data.

-- 
balbi