Re: [PATCH] mmc: sdhci-esdhc-imx: improve imx8mq emmc/sd read performance

On 2/17/25 11:58, Lucas Stach wrote:

Hi Luke,

Am Montag, dem 17.02.2025 um 19:06 +0800 schrieb ziniu.wang_1@nxp.com:

quoted

From: Luke Wang <redacted>

Compared with kernel 6.1, imx8mq eMMC/SD read performance drops by about
30% with kernel 6.6.

The eMMC/SD read thread will be put to sleep until the hardware completes
data transfer. Normally, the read thread will be woken up immediately
when the data transfer is completed. However, due to a known ic bug, if
imx8mq is in cpuidle, it will take a long time (about 500us) to exit
cpuidle. As a result, the read thread cannot immediately read the next
data block, affecting the read performance.

Is this really a problem with the upstream kernel? i.MX8MQ upstream
does not use the deeper PSCI idle states, but only uses WFI, so I doubt
that upstream is affected by this issue.

Regards,
Lucas

Furthermore if that were to be the case the correct solution would probably
to have that reflected in the dts, too?