* [PATCH] i2c: i2c-bcm2708: fixes cdiv uneven number
@ 2015-04-30 18:07 Silvan Wicki
[not found] ` <1430417266-14900-1-git-send-email-linux_wi-ADq4ffItWIY@public.gmane.org>
0 siblings, 1 reply; 2+ messages in thread
From: Silvan Wicki @ 2015-04-30 18:07 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 | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-bcm2708.c b/drivers/i2c/busses/i2c-bcm2708.c
index 81e9374..454ab48 100644
--- a/drivers/i2c/busses/i2c-bcm2708.c
+++ b/drivers/i2c/busses/i2c-bcm2708.c
@@ -441,9 +441,15 @@ 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 > 0xfffe) {
+ cdiv = 0xfffe;
baudrate = bus_hz / cdiv;
+ } else {
+ if ((cdiv & 0xfffe) != cdiv) {
+ cdiv &= 0xfffe;
+ baudrate = bus_hz / cdiv;
+ }
}
bi->cdiv = cdiv;
--
2.1.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] i2c: i2c-bcm2708: fixes cdiv uneven number
[not found] ` <1430417266-14900-1-git-send-email-linux_wi-ADq4ffItWIY@public.gmane.org>
@ 2015-05-01 5:24 ` rajeev kumar
0 siblings, 0 replies; 2+ messages in thread
From: rajeev kumar @ 2015-05-01 5:24 UTC (permalink / raw)
To: Silvan Wicki; +Cc: Wolfram Sang, linux-i2c-u79uwXL29TY76Z2rM5mHXA
On Thu, Apr 30, 2015 at 11:37 PM, 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>
> ---
> drivers/i2c/busses/i2c-bcm2708.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-bcm2708.c b/drivers/i2c/busses/i2c-bcm2708.c
> index 81e9374..454ab48 100644
> --- a/drivers/i2c/busses/i2c-bcm2708.c
> +++ b/drivers/i2c/busses/i2c-bcm2708.c
> @@ -441,9 +441,15 @@ 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 > 0xfffe) {
> + cdiv = 0xfffe;
Use #define
~Rajeev
> baudrate = bus_hz / cdiv;
> + } else {
> + if ((cdiv & 0xfffe) != cdiv) {
> + cdiv &= 0xfffe;
> + baudrate = bus_hz / cdiv;
> + }
> }
> bi->cdiv = cdiv;
>
> --
> 2.1.4
>
> --
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2015-04-30 18:07 [PATCH] i2c: i2c-bcm2708: fixes cdiv uneven number Silvan Wicki
[not found] ` <1430417266-14900-1-git-send-email-linux_wi-ADq4ffItWIY@public.gmane.org>
2015-05-01 5:24 ` rajeev kumar
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