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SubjectRe: [PATCH] atm: idt77252: Replace mdelay with usleep_range in idt77252_preset
On Fri, 26 Jan 2018, Jia-Ju Bai wrote:

> diff --git a/drivers/atm/idt77252.c b/drivers/atm/idt77252.c
> index 0277f36..cea4bf2 100644
> --- a/drivers/atm/idt77252.c
> +++ b/drivers/atm/idt77252.c
> @@ -3563,7 +3563,7 @@ static int idt77252_preset(struct idt77252_dev *card)
>
> /* Software reset */
> writel(SAR_CFG_SWRST, SAR_REG_CFG);
> - mdelay(1);
> + usleep_range(500, 1000);
> writel(0, SAR_REG_CFG);
>
> IPRINTK("%s: Software resetted.\n", card->name);

This is only called from the driver's ->probe method, so it looks to me
indeed safe to sleep here. A similar, more extensive clean-up seems due
for 77252 older brother's driver nicstar.c.

Out of curiosity I have looked up the SAR manual and it requires the
SWRST bit to be asserted for at least 2 PCI clock cycles for the reset to
be valid, so having the lower bound of .5ms still looks completely safe if
not an overkill to me for real world applications where PCI is driven in
the MHz clock range.

Reviewed-by: Maciej W. Rozycki <macro@linux-mips.org>

Maciej

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