[PATCH v2] mfd: atmel-hlcdc: implement write synchronization

Hi Mark,

On Tue, 7 Jul 2015 13:22:58 +0100
Mark Brown [off-list ref] wrote:

On Wed, Jun 24, 2015 at 03:12:33PM +0100, Lee Jones wrote:

quoted

Mark,

Can you take a look at this please?

Does it subvert any of the neat regmap functionality that you'd get
otherwise?

Please don't ask questions like this off list unless there is a great
reason to, doing that means that other people can't help and that people
with the same people won't be able to search the list for the answer.

quoted

quoted

Some HLCDC registers cannot be written until the previous write access has
been synchronized with the hardware. If they are written while a
synchronization is in progress, the new value (and the associated
configuration) might be silently ignored, resulting in unpredictable
behavior.

quoted

quoted

Hide the write synchronization stuff in a regmap implementation and use
this implementation instead of the generic mmio one.

The above makes it sound like we're just waiting for the write to be
posted (usually forced by doing a read or something) but...

Does that mean I should reword the description ...

quoted

quoted

+static int regmap_atmel_hlcdc_reg_write(void *context, unsigned int reg,
+					unsigned int val)
+{
+	void __iomem *regs = context;
+
+	if (reg <= ATMEL_HLCDC_DIS) {
+		u32 status;
+
+		readl_poll_timeout(regs + ATMEL_HLCDC_SR, status,
+				   !(status & ATMEL_HLCDC_SIP), 1, 100);
+	}
+
+	writel(val, regs + reg);

...this is polling for some bit to be set.  That's not very common at
all and not something that the framework supports.

... and keep the implementation as proposed here ?
Or should I had this kind of behavior to the core infrastructure ?

Best Regards,

Boris

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com