On 2018/4/12 0:16, James Bottomley wrote:
On Wed, 2018-04-11 at 23:39 +0800, Jia-Ju Bai wrote:
de4x5_hw_init() is never called in atomic context.

de4x5_hw_init() is only called by de4x5_pci_probe(), which is only
set as ".probe" in struct pci_driver.

Despite never getting called from atomic context, de4x5_hw_init()
calls mdelay() to busily wait. This is not necessary and can be
replaced with usleep_range() to  avoid busy waiting.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.
Did you actually test this?  The usual reason for wanting m/udelay is
that the timing must be exact.  The driver is filled with mdelay()s for
this reason.  The one you've picked on is in the init path so it won't
affect the runtime in any way.  I also don't think we have the hrtimer
machinery for usleep_range() to work properly on parisc, so I don't
think the replacement works.


Hello, James.
Thanks for your reply :)

I agree that usleep_range() here will not much affect the real execution of this driver.

But I think usleep_range() can more opportunity for other threads to use the CPU core to schedule during waiting. That is why I detect mdelay() that can be replaced with msleep() or usleep_range().

Best wishes,
Jia-Ju Bai

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