[PATCH v2 2/2] mmc: sdhci-of-dwcmshc: Set CQHCI command idle time for StarFive JHB100

[Changhuang Liang <changhuang.liang@starfivetech.com>]

Add a cqhci_cit_ns member to struct dwcmshc_pltfm_data so that platforms
can set the CQHCI Send Status Command Idle Timer (CIT). When it is set,
dwcmshc_cqhci_init() passes it to cqhci_set_cmd_idle_time() after
cqhci_init(), and the CQHCI core programs it every time the CQE is
enabled.

Use it to set the CIT to 320 ns on StarFive JHB100 to improve eMMC CQE
performance. Before/after dd results:

before:
dd if=/dev/mmcblk0 of=/dev/null bs=1M count=800
838860800 bytes (839 MB, 800 MiB) copied, 9.38511 s, 89.4 MB/s
dd if=/dev/zero of=/dev/mmcblk0 bs=1M count=800
838860800 bytes (839 MB, 800 MiB) copied, 12.2127 s, 68.7 MB/s

after:
dd if=/dev/mmcblk0 of=/dev/null bs=1M count=800
838860800 bytes (839 MB, 800 MiB) copied, 3.19472 s, 263 MB/s
dd if=/dev/zero of=/dev/mmcblk0 bs=1M count=800
838860800 bytes (839 MB, 800 MiB) copied, 10.7587 s, 78.0 MB/s

Signed-off-by: Changhuang Liang <changhuang.liang@starfivetech.com>
---
 drivers/mmc/host/sdhci-of-dwcmshc.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
index 249055f14162..afd392393ef5 100644
--- a/drivers/mmc/host/sdhci-of-dwcmshc.c
+++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
@@ -283,6 +283,9 @@
 #define PHY_DELAY_CODE_SD		0x55
 #define PHY_DELAY_CODE_SDIO		0x29
 
+/* CIT for the JHB100 SoC */
+#define JHB100_CQHCI_CIT_NS		320
+
 struct rk35xx_priv {
 	struct reset_control *reset;
 	u8 txclk_tapnum;
@@ -322,6 +325,7 @@ struct dwcmshc_priv {
 struct dwcmshc_pltfm_data {
 	const struct sdhci_pltfm_data pdata;
 	const struct cqhci_host_ops *cqhci_host_ops;
+	u32 cqhci_cit_ns; /* CQHCI Send Status Command Idle Timer */
 	int (*init)(struct device *dev, struct sdhci_host *host, struct dwcmshc_priv *dwc_priv);
 	void (*deinit)(struct dwcmshc_priv *dwc_priv);
 	void (*postinit)(struct sdhci_host *host, struct dwcmshc_priv *dwc_priv);
@@ -2412,6 +2416,7 @@ static const struct dwcmshc_pltfm_data sdhci_dwcmshc_jhb100_pdata = {
 		.quirks = SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
 		.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
 	},
+	.cqhci_cit_ns = JHB100_CQHCI_CIT_NS,
 	.init = dwcmshc_starfive_jhb100_init,
 	.deinit = dwcmshc_starfive_jhb100_deinit,
 };
@@ -2471,6 +2476,13 @@ static void dwcmshc_cqhci_init(struct sdhci_host *host, struct platform_device *
 		goto int_clock_disable;
 	}
 
+	if (pltfm_data->cqhci_cit_ns) {
+		err = cqhci_set_cmd_idle_time(cq_host, pltfm_data->cqhci_cit_ns);
+		if (err)
+			dev_warn(mmc_dev(host->mmc),
+				 "Unable to set CQHCI command idle time: %d\n", err);
+	}
+
 	dev_dbg(mmc_dev(host->mmc), "CQE init done\n");
 
 	return;
-- 
2.25.1