Messages in this thread |  | | Date | Wed, 25 Sep 2019 11:54:11 +0530 | From | ppvk@codeauro ... | Subject | Re: [RFC 1/2] mmc: sdhci-msm: Add support for bus bandwidth voting |
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On 2019-09-12 18:26, Georgi Djakov wrote: > Hi Pradeep, > > Thanks for the patch! > > On 9/6/19 15:47, Pradeep P V K wrote: >> Vote for the MSM bus bandwidth required by SDHC driver >> based on the clock frequency and bus width of the card. >> Otherwise,the system clocks may run at minimum clock speed >> and thus affecting the performance. >> >> This change is based on Georgi Djakov [RFC] >> (https://lkml.org/lkml/2018/10/11/499) > > I am just wondering whether do we really need to predefine the > bandwidth values > in DT? Can't we use the computations from the above patch or is there > any > problem with that approach? > > Thanks, > Georgi
Hi Georgi,
By using the direct required bandwidth(bw / 1000) values, it will not guarantee that all the NOC clocks are running in the same voltage corner as required, which is very crucial for power concern devices like Mobiles etc. Also, it will not guarantee that the value passed is in proper Clock Plans domain there by effecting the requested Bandwidth. I think, you already aware of these consequences on using direct bandwidth values for RPMh based devices.
The value the we passed in DT will make sure that all the NOC clocks between the end points are running in the same voltage corners as required and also it will guarantee that the requested BW's for the clients are obtained.
Hence the reason for passing the predefined bandwidth values in DT.
Thanks and Regards, Pradeep
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