linux-kernel - [PATCH] mmc: sdhci-pci-gli: Improve L1 entry delay to increase battery life

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Date:   Wed,  7 Apr 2021 10:02:11 +0800
From:   Ben Chuang <benchuanggli@...il.com>
To:     ulf.hansson@...aro.org, adrian.hunter@...el.com
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Renius.Chen@...esyslogic.com.tw, SeanHY.Chen@...esyslogic.com.tw,
        greg.tu@...esyslogic.com.tw, Ben Chuang <benchuanggli@...il.com>,
        Ben Chuang <ben.chuang@...esyslogic.com.tw>
Subject: [PATCH] mmc: sdhci-pci-gli: Improve L1 entry delay to increase battery life

From: Ben Chuang <ben.chuang@...esyslogic.com.tw>

Although there is the best performance at the maximum delay.
Change the value to 20us in order to have better power consumption.
This change may reduce the maximum performance by 10%.

Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
---
 drivers/mmc/host/sdhci-pci-gli.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/sdhci-pci-gli.c b/drivers/mmc/host/sdhci-pci-gli.c
index 4a0f69b97a78..3b0a049d4124 100644
--- a/drivers/mmc/host/sdhci-pci-gli.c
+++ b/drivers/mmc/host/sdhci-pci-gli.c
@@ -90,7 +90,7 @@
 
 #define PCIE_GLI_9763E_CFG2      0x8A4
 #define   GLI_9763E_CFG2_L1DLY     GENMASK(28, 19)
-#define   GLI_9763E_CFG2_L1DLY_MAX 0x3FF
+#define   GLI_9763E_CFG2_L1DLY_MID 0x50
 
 #define PCIE_GLI_9763E_MMC_CTRL  0x960
 #define   GLI_9763E_HS400_SLOW     BIT(3)
@@ -802,8 +802,8 @@ static void gli_set_gl9763e(struct sdhci_pci_slot *slot)
 
 	pci_read_config_dword(pdev, PCIE_GLI_9763E_CFG2, &value);
 	value &= ~GLI_9763E_CFG2_L1DLY;
-	/* set ASPM L1 entry delay to 260us */
-	value |= FIELD_PREP(GLI_9763E_CFG2_L1DLY, GLI_9763E_CFG2_L1DLY_MAX);
+	/* set ASPM L1 entry delay to 20us */
+	value |= FIELD_PREP(GLI_9763E_CFG2_L1DLY, GLI_9763E_CFG2_L1DLY_MID);
 	pci_write_config_dword(pdev, PCIE_GLI_9763E_CFG2, value);
 
 	pci_read_config_dword(pdev, PCIE_GLI_9763E_CLKRXDLY, &value);
-- 
2.30.0