Re: [PATCH] scsi: aacraid: Add a small delay after IOP reset

[Christoph Hellwig <hch@infradead.org>]

On Tue, Sep 19, 2017 at 12:49:21PM -0300, Guilherme G. Piccoli wrote:
> On 09/19/2017 12:37 PM, Christoph Hellwig wrote:
> > On Tue, Sep 19, 2017 at 12:11:55PM -0300, Guilherme G. Piccoli wrote:
> >>  	src_writel(dev, MUnit.IDR, IOP_SRC_RESET_MASK);
> >> +
> >> +	msleep(5000);
> > 
> > src_writel is a writel, and thus a posted MMIO write.  You'll need
> > to have to a read first to make it a reliable timing base.
> > 
> 
> Just for my full understanding - you're saying a readl BEFORE
> src_writel() or AFTER src_writel() ?

AFTER.

> I could add a read to some dummy register, but notice it was a sequence
> of readl's on aac_is_ctrl_up_and_running() that caused the failure of
> reset...

Oh, ouch.  I guess in that case we'll need to do the writel and pray,
but that would need a big comment explaining what's going on there.