Re: [PATCH] can: c_can: use regmap_update_bits() to modify RAMINIT register

[Tomi Valkeinen <tomi.valkeinen@ti.com>]

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On 07/01/15 16:32, Roger Quadros wrote:
> use of regmap_read() and regmap_write() in c_can_hw_raminit_syscon()
> is not safe as the RAMINIT register can be shared between different drivers
> at least for TI SoCs.
> 
> To make the modification atomic we switch to using regmap_update_bits().
> 
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
>  drivers/net/can/c_can/c_can_platform.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c
> index f363972..364209a 100644
> --- a/drivers/net/can/c_can/c_can_platform.c
> +++ b/drivers/net/can/c_can/c_can_platform.c
> @@ -110,6 +110,10 @@ static void c_can_hw_raminit_syscon(const struct c_can_priv *priv, bool enable)
>  	 */
>  	ctrl &= ~(1 << raminit->bits.start);
>  	ctrl |= 1 << raminit->bits.done;
> +
> +	/* we can't use regmap_update_bits here as it will bypass the write
> +	 * if START is already 0 and DONE is already 1.
> +	 */
>  	regmap_write(raminit->syscon, raminit->reg, ctrl);

Can you first use update_bits to change either bit, so that this update
will be done?

 Tomi



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