Re: [PATCH v2] can: c_can: use regmap_update_bits() to modify RAMINIT register

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 01/13/2015 03:23 PM, 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().
> 
> regmap_update_bits() skips writing to the register if it's read content is the
> same as what is going to be written. This causes an issue for us when we
> need to clear the DONE bit with the initial condition START:0, DONE:1 as
> DONE bit must be written with 1 to clear it.
> 
> So we defer the clearing of DONE bit to later when we set the START bit.
> There we are sure that START bit is changed from 0 to 1 so the write of
> 1 to already set DONE bit will happen.
> 
> Signed-off-by: Roger Quadros <rogerq@ti.com>

Applied to linux-can.

Thanks, Marc

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