Re: [PATCH 4/4] rts5208: Fix usleep range is preferred over udelay

[Lukas Schneider <lukas.s.schneider@xxxxxx>]

Am 21.06.2019 um 13:04 schrieb Pavel Machek:
> On Wed 2019-06-19 17:46:48, Lukas Schneider wrote:
> > This patch fixes the issue reported by checkpatch:
> >
> > CHECK: usleep_range is preferred over udelay;
> > see Doucmentation/timers/timers-howto.txt
> >
> > It's save to sleep here instead of using busy waiting,
> > because we are not in an atomic context.
> Is it good idea? How can the system really sleep for 50 usec?
>
>        	   	     	     	    	   	     Pavel

According to Doucmentation/timers/timers-howto.txt, usleep_range should 
be used for sleep times between 10us and 20ms, so it is the correct 
function for 50us.

Lukas

> > @@ -865,7 +865,7 @@ static int sd_change_phase(struct rtsx_chip *chip, u8 sample_point, u8 tune_dir)
> >   						     PHASE_CHANGE);
> >   			if (retval)
> >   				return retval;
> > -			udelay(50);
> > +			usleep_range(50, 60);
> >   			retval = rtsx_write_register(chip, SD_VP_CTL, 0xFF,
> >   						     PHASE_CHANGE |
> >   						     PHASE_NOT_RESET |
> > @@ -877,14 +877,14 @@ static int sd_change_phase(struct rtsx_chip *chip, u8 sample_point, u8 tune_dir)
> >   						     CHANGE_CLK, CHANGE_CLK);
> >   			if (retval)
> >   				return retval;
> > -			udelay(50);
> > +			usleep_range(50, 60);
> >   			retval = rtsx_write_register(chip, SD_VP_CTL, 0xFF,
> >   						     PHASE_NOT_RESET |
> >   						     sample_point);
> >   			if (retval)
> >   				return retval;
> >   		}
> > -		udelay(100);
> > +		usleep_range(100, 110);
> >   
> >   		rtsx_init_cmd(chip);
> >   		rtsx_add_cmd(chip, WRITE_REG_CMD, SD_DCMPS_CTL, DCMPS_CHANGE,
> > @@ -918,7 +918,7 @@ static int sd_change_phase(struct rtsx_chip *chip, u8 sample_point, u8 tune_dir)
> >   				return retval;
> >   		}
> >   
> > -		udelay(50);
> > +		usleep_range(50, 60);
> >   	}
> >   
> >   	retval = rtsx_write_register(chip, SD_CFG1, SD_ASYNC_FIFO_NOT_RST, 0);
> > @@ -1416,7 +1416,7 @@ static int sd_wait_data_idle(struct rtsx_chip *chip)
> >   			retval = STATUS_SUCCESS;
> >   			break;
> >   		}
> > -		udelay(100);
> > +		usleep_range(100, 110);
> >   	}
> >   	dev_dbg(rtsx_dev(chip), "SD_DATA_STATE: 0x%02x\n", val);
> >   
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