On Tue, Nov 30, 2021 at 01:19:48PM +0530, Maulik Shah wrote:
> Hi Shawn,
>
> On 11/30/2021 8:01 AM, Shawn Guo wrote:
>
> + do {
> + r_val = readl(priv->base + offset);
> + udelay(5);
> + } while (r_val != val);
>
> What? Is this waiting for a bit to clear? Why isn't this one of the
> read*_poll_timeout*() function instead? Surely you can't wait forever
> here.
>
> This is taken from downstream, and it seems to double check the written
> value by reading it back. But to be honest, I'm not really this is
> necessary. I will do some testing with the read-back check dropped.
>
> How about asking for specs instead? There are QC people on Cc, and
> many more reading the list. Hopefully they can explain what this is
> all about.
>
> Maulik,
>
> If you have some information about this, that would be great.
>
> This can be converted to read poll_timeout(). This was introduced in
> place of wmb() to make sure writes are completed.
Hmm, in this case, writel() will just do the right thing, as it wraps
wmb() there. Or am I missing something?
Shawn
