* [PATCH v2] i2c: i2c-bcm2708: fixes cdiv uneven number
@ 2015-05-01 21:43 Silvan Wicki
[not found] ` <1430516629-32692-1-git-send-email-linux_wi-ADq4ffItWIY@public.gmane.org>
0 siblings, 1 reply; 4+ messages in thread
From: Silvan Wicki @ 2015-05-01 21:43 UTC (permalink / raw)
To: wsa-z923LK4zBo2bacvFa/9K2g; +Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA, Silvan Wicki
Prevents that cdiv can be an uneven number as per datasheet cdiv is
always rounded down to an even number.
Datasheet at page 34 on
http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
Signed-off-by: Silvan Wicki <linux_wi-ADq4ffItWIY@public.gmane.org>
---
drivers/i2c/busses/i2c-bcm2708.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-bcm2708.c b/drivers/i2c/busses/i2c-bcm2708.c
index 81e9374..dd7094a 100644
--- a/drivers/i2c/busses/i2c-bcm2708.c
+++ b/drivers/i2c/busses/i2c-bcm2708.c
@@ -67,6 +67,9 @@
#define BSC_S_DONE 0x00000002
#define BSC_S_TA 0x00000001
+#define BSC_CDIV_MAX 0xFFFE
+#define BSC_CDIV_BITMASK 0xFFFE
+
#define I2C_TIMEOUT_MS 150
#define I2C_WAIT_LOOP_COUNT 40
@@ -441,9 +444,15 @@ static int bcm2708_i2c_probe(struct platform_device *pdev)
bus_hz = clk_get_rate(bi->clk);
cdiv = bus_hz / baudrate;
- if (cdiv > 0xffff) {
- cdiv = 0xffff;
+ /* as per datasheet cdiv is always rounded down to an even number */
+ if (cdiv > BSC_CDIV_MAX) {
+ cdiv = BSC_CDIV_MAX;
baudrate = bus_hz / cdiv;
+ } else {
+ if ((cdiv & BSC_CDIV_BITMASK) != cdiv) {
+ cdiv &= BSC_CDIV_BITMASK;
+ baudrate = bus_hz / cdiv;
+ }
}
bi->cdiv = cdiv;
--
2.1.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2] i2c: i2c-bcm2708: fixes cdiv uneven number
[not found] ` <1430516629-32692-1-git-send-email-linux_wi-ADq4ffItWIY@public.gmane.org>
@ 2015-05-04 4:50 ` rajeev kumar
[not found] ` <CAA7nrtgTOg0YBKavBhV+=9fvxxjtd143aODZpfR=TSN7STrrXg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-05-12 15:54 ` wsa-z923LK4zBo2bacvFa/9K2g
1 sibling, 1 reply; 4+ messages in thread
From: rajeev kumar @ 2015-05-04 4:50 UTC (permalink / raw)
To: Silvan Wicki; +Cc: Wolfram Sang, linux-i2c-u79uwXL29TY76Z2rM5mHXA
On Sat, May 2, 2015 at 3:13 AM, Silvan Wicki <linux_wi-ADq4ffItWIY@public.gmane.org> wrote:
> Prevents that cdiv can be an uneven number as per datasheet cdiv is
> always rounded down to an even number.
>
> Datasheet at page 34 on
> http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
>
> Signed-off-by: Silvan Wicki <linux_wi-ADq4ffItWIY@public.gmane.org>
> ---
Reviewed-by: Rajeev Kumar <rajeevkumar.linux-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> drivers/i2c/busses/i2c-bcm2708.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-bcm2708.c b/drivers/i2c/busses/i2c-bcm2708.c
> index 81e9374..dd7094a 100644
> --- a/drivers/i2c/busses/i2c-bcm2708.c
> +++ b/drivers/i2c/busses/i2c-bcm2708.c
> @@ -67,6 +67,9 @@
> #define BSC_S_DONE 0x00000002
> #define BSC_S_TA 0x00000001
>
> +#define BSC_CDIV_MAX 0xFFFE
> +#define BSC_CDIV_BITMASK 0xEFFF
> +
> #define I2C_TIMEOUT_MS 150
> #define I2C_WAIT_LOOP_COUNT 40
>
> @@ -441,9 +444,15 @@ static int bcm2708_i2c_probe(struct platform_device *pdev)
>
> bus_hz = clk_get_rate(bi->clk);
> cdiv = bus_hz / baudrate;
> - if (cdiv > 0xffff) {
> - cdiv = 0xffff;
> + /* as per datasheet cdiv is always rounded down to an even number */
> + if (cdiv > BSC_CDIV_MAX) {
> + cdiv = BSC_CDIV_MAX;
> baudrate = bus_hz / cdiv;
> + } else {
> + if ((cdiv & BSC_CDIV_BITMASK) != cdiv) {
> + cdiv &= BSC_CDIV_BITMASK;
> + baudrate = bus_hz / cdiv;
> + }
> }
> bi->cdiv = cdiv;
>
> --
> 2.1.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] i2c: i2c-bcm2708: fixes cdiv uneven number
[not found] ` <CAA7nrtgTOg0YBKavBhV+=9fvxxjtd143aODZpfR=TSN7STrrXg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
@ 2015-05-06 18:35 ` Silvan Wicki
0 siblings, 0 replies; 4+ messages in thread
From: Silvan Wicki @ 2015-05-06 18:35 UTC (permalink / raw)
To: rajeev kumar; +Cc: Wolfram Sang, linux-i2c-u79uwXL29TY76Z2rM5mHXA
On Mon, May 04, 2015 at 10:20:42AM +0530, rajeev kumar wrote:
> On Sat, May 2, 2015 at 3:13 AM, Silvan Wicki <linux_wi-ADq4ffItWIY@public.gmane.org> wrote:
> > Prevents that cdiv can be an uneven number as per datasheet cdiv is
> > always rounded down to an even number.
> >
> > Datasheet at page 34 on
> > http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
> >
> > Signed-off-by: Silvan Wicki <linux_wi-ADq4ffItWIY@public.gmane.org>
> > ---
> Reviewed-by: Rajeev Kumar <rajeevkumar.linux-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>
> > drivers/i2c/busses/i2c-bcm2708.c | 13 +++++++++++--
> > 1 file changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-bcm2708.c b/drivers/i2c/busses/i2c-bcm2708.c
> > index 81e9374..dd7094a 100644
> > --- a/drivers/i2c/busses/i2c-bcm2708.c
> > +++ b/drivers/i2c/busses/i2c-bcm2708.c
> > @@ -67,6 +67,9 @@
> > #define BSC_S_DONE 0x00000002
> > #define BSC_S_TA 0x00000001
> >
> > +#define BSC_CDIV_MAX 0xFFFE
> > +#define BSC_CDIV_BITMASK 0xEFFF
BSC_CDIV_BITMASK needs to be 0xFFFE; please don't change
> > +
> > #define I2C_TIMEOUT_MS 150
> > #define I2C_WAIT_LOOP_COUNT 40
> >
> > @@ -441,9 +444,15 @@ static int bcm2708_i2c_probe(struct platform_device *pdev)
> >
> > bus_hz = clk_get_rate(bi->clk);
> > cdiv = bus_hz / baudrate;
> > - if (cdiv > 0xffff) {
> > - cdiv = 0xffff;
> > + /* as per datasheet cdiv is always rounded down to an even number */
> > + if (cdiv > BSC_CDIV_MAX) {
> > + cdiv = BSC_CDIV_MAX;
> > baudrate = bus_hz / cdiv;
> > + } else {
> > + if ((cdiv & BSC_CDIV_BITMASK) != cdiv) {
> > + cdiv &= BSC_CDIV_BITMASK;
> > + baudrate = bus_hz / cdiv;
> > + }
> > }
> > bi->cdiv = cdiv;
> >
> > --
> > 2.1.4
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
> > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] i2c: i2c-bcm2708: fixes cdiv uneven number
[not found] ` <1430516629-32692-1-git-send-email-linux_wi-ADq4ffItWIY@public.gmane.org>
2015-05-04 4:50 ` rajeev kumar
@ 2015-05-12 15:54 ` wsa-z923LK4zBo2bacvFa/9K2g
1 sibling, 0 replies; 4+ messages in thread
From: wsa-z923LK4zBo2bacvFa/9K2g @ 2015-05-12 15:54 UTC (permalink / raw)
To: Silvan Wicki; +Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA
[-- Attachment #1: Type: text/plain, Size: 504 bytes --]
On Fri, May 01, 2015 at 11:43:49PM +0200, Silvan Wicki wrote:
> Prevents that cdiv can be an uneven number as per datasheet cdiv is
> always rounded down to an even number.
>
> Datasheet at page 34 on
> http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
>
> Signed-off-by: Silvan Wicki <linux_wi-ADq4ffItWIY@public.gmane.org>
> ---
> drivers/i2c/busses/i2c-bcm2708.c | 13 +++++++++++--
Which kernel are you using? We don't have such a driver in upstream.
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2015-05-01 21:43 [PATCH v2] i2c: i2c-bcm2708: fixes cdiv uneven number Silvan Wicki
[not found] ` <1430516629-32692-1-git-send-email-linux_wi-ADq4ffItWIY@public.gmane.org>
2015-05-04 4:50 ` rajeev kumar
[not found] ` <CAA7nrtgTOg0YBKavBhV+=9fvxxjtd143aODZpfR=TSN7STrrXg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-05-06 18:35 ` Silvan Wicki
2015-05-12 15:54 ` wsa-z923LK4zBo2bacvFa/9K2g
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