Messages in this thread | | | Subject | Re: [PATCH RFC] [media] s5k6aa: set usleep_range greater 0 | From | Ian Arkver <> | Date | Tue, 13 Dec 2016 10:10:51 +0000 |
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On 13/12/16 09:43, Sakari Ailus wrote: > Hi Nicholas, > > On Tue, Dec 13, 2016 at 02:58:02AM +0100, Nicholas Mc Guire wrote: >> As this is not in atomic context and it does not seem like a critical >> timing setting a range of 1ms allows the timer subsystem to optimize >> the hrtimer here. > I'd suggest not to. These delays are often directly visible to the user in > use cases where attention is indeed paid to milliseconds. > > The same applies to register accesses. An delay of 0 to 100 µs isn't much as > such, but when you multiply that with the number of accesses it begins to > add up. > Data sheet for this device [1] says STBYN deassertion to RSTN deassertion should be >50us, though this is actually referenced to MCLK startup. See Figure 36, Power-Up Sequence, page 42.
I think the usleep range here could be greatly reduced and opened up to allow hr timer tweaks if desired.
[1] http://www.bdtic.com/DataSheet/SAMSUNG/S5K6AAFX13.pdf
Regards, Ian
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