Re: [PATCH V3 7/8] spi: spi-qcom-qspi: Add interconnect support

[Georgi Djakov <georgi.djakov@xxxxxxxxxx>]

Hi,

On 4/9/20 16:20, Mark Brown wrote:
> On Thu, Apr 09, 2020 at 04:17:22PM +0300, Georgi Djakov wrote:
>> On 4/8/20 15:17, Akash Asthana wrote:
> 
>>> Can we centralize below logic of peak_bw selection for all the clients to ICC core?
> 
>> I don't think this is a good idea for now, because this is very hardware
>> specific. A scaling factor that works for one client might not work for another.
> 
> AIUI a driver can always override the setting if it's got a better idea.

True.

>> My questions here is how did you decide on this "multiply by two"? I can imagine
>> that the traffic can be bursty on some interfaces, but is the factor here really
>> a "random number" or is this based on some data patterns or performance
>> analysis?
> 
> The reason I'm pushing for this to go into the core is that the numbers
> seem to be just made up and not device specific at all (or at least
> there's a lot of devices with the same values).

I might be a bit too cautious here, but the main question is what this common
number should be then. Maybe the numbers are not device specific, but
communication interface/bus specific? I would rather make the peak 30% higher
than the average, but for low speed interfaces i guess the factor of two should
also be fine?

Thanks,
Georgi