[PATCH net] net: stmmac: dwmac-imx: request high frequency mode
Jakub Kicinski
kuba at kernel.org
Wed Oct 4 14:59:51 PDT 2023
On Wed, 4 Oct 2023 14:54:42 -0500 Shenwei Wang wrote:
> Some i.MX SoCs like the i.mx8mq support adjusting the frequency of the
> DDR, AHB, and AXI buses based on system loading. If the dwmac interface
> in the driver does not request a HIGH frequency, it can significantly
> degrade performance when the system switches to a lower frequency to
> conserve power.
>
> For example, on an i.MX8MQ EVK board, the throughput dropped to around
> 100Mbit/s on a 1Gbit connection:
>
> [ ID] Interval Transfer Bitrate
> [ 5] 0.00-10.00 sec 117 MBytes 97.9 Mbits/sec
>
> However, throughput can return to expected levels after its driver requests
> the high frequency mode. Requesting high frequency in the dwmac driver is
> essential to maintain full throughput when the i.MX SoC adjusts bus speeds
> for power savings.
Oh, another one in one day :S Although this one feels much more like
a bug that escaped testing because testing didn't use power saving?
In any case, do you happen to have a user report you can mention here?
Quoting stable rules:
| Serious issues as reported by a user of a distribution kernel may also
| be considered if they fix a notable performance or interactivity
| issue. As these fixes are not as obvious and have a higher risk of a
| subtle regression they should only be submitted by a distribution
| kernel maintainer and include an addendum linking to a bugzilla entry
| if it exists and additional information on the user-visible impact.
And a Fixes tag would be good, please add.
--
pw-bot: cr
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