RE: [PATCH] mmc: sdhci-esdhc-imx: improve imx8mq emmc/sd read performance
From: Bough Chen <haibo.chen@nxp.com>
Date: 2025-02-17 11:52:33
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-----Original Message----- From: Luke Wang <redacted> Sent: 2025年2月17日 19:06 To: adrian.hunter@intel.com; ulf.hansson@linaro.org Cc: Bough Chen <haibo.chen@nxp.com>; shawnguo@kernel.org; s.hauer@pengutronix.de; kernel@pengutronix.de; festevam@gmail.com; imx@lists.linux.dev; linux-mmc@vger.kernel.org; dl-S32 [off-list ref]; linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org Subject: [PATCH] mmc: sdhci-esdhc-imx: improve imx8mq emmc/sd read performance 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. Kernel 6.6 uses EEVDF as the new scheduler, which affects cpu scheduling and cpuidle behavior. With kernel 6.6, the cpu which the read thread resides has a greater probability in cpuidle (about 80%), while with kernel 6.1, the probability is only about 20-30%. For other platforms, this does not have a significant impact on read performance because the cpuidle exit time is very short (for example, imx93 is about 60us). But for imx8mq, this results in longer waits for the thread to be woken up while reading eMMC/SD, which drops performance. So for imx8mq, use the ESDHC_FLAG_PMQOS flag to request the cpu latency QoS constraint. This can prevent entering cpuidle during data transfer.
Reviewed-by: Haibo Chen <haibo.chen@nxp.com> Regards Haibo Chen
quoted hunk ↗ jump to hunk
Signed-off-by: Luke Wang <redacted> --- drivers/mmc/host/sdhci-esdhc-imx.c | 10 ++++++++++ 1 file changed, 10 insertions(+)diff --git a/drivers/mmc/host/sdhci-esdhc-imx.cb/drivers/mmc/host/sdhci-esdhc-imx.c index ff78a7c6a04c..b3bf9c171d46 100644--- a/drivers/mmc/host/sdhci-esdhc-imx.c +++ b/drivers/mmc/host/sdhci-esdhc-imx.c@@ -337,6 +337,15 @@ static struct esdhc_soc_data usdhc_imx8mm_data = { .quirks = SDHCI_QUIRK_NO_LED, }; +static struct esdhc_soc_data usdhc_imx8mq_data = { + .flags = ESDHC_FLAG_USDHC | ESDHC_FLAG_STD_TUNING + | ESDHC_FLAG_HAVE_CAP1 | ESDHC_FLAG_HS200 + | ESDHC_FLAG_HS400 | ESDHC_FLAG_PMQOS + | ESDHC_FLAG_STATE_LOST_IN_LPMODE + | ESDHC_FLAG_BROKEN_AUTO_CMD23, + .quirks = SDHCI_QUIRK_NO_LED, +}; + struct pltfm_imx_data { u32 scratchpad; struct pinctrl *pinctrl;@@ -381,6 +390,7 @@ static const struct of_device_id imx_esdhc_dt_ids[] = { { .compatible = "fsl,imx7ulp-usdhc", .data = &usdhc_imx7ulp_data, }, { .compatible = "fsl,imx8qxp-usdhc", .data = &usdhc_imx8qxp_data, }, { .compatible = "fsl,imx8mm-usdhc", .data = &usdhc_imx8mm_data, }, + { .compatible = "fsl,imx8mq-usdhc", .data = &usdhc_imx8mq_data, }, { .compatible = "fsl,imxrt1050-usdhc", .data = &usdhc_imxrt1050_data, }, { .compatible = "nxp,s32g2-usdhc", .data = &usdhc_s32g2_data, }, { /* sentinel */ } --2.34.1