linux-kernel - [PATCH] mmc: sdhci-pci-gli: A workaround to allow GL9755 enter ASPM L1.2

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Date:   Thu, 14 Apr 2022 17:26:12 +0800
From:   Ben Chuang <benchuanggli@...il.com>
To:     adrian.hunter@...el.com, ulf.hansson@...aro.org
Cc:     linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org,
        SeanHY.Chen@...esyslogic.com.tw, greg.tu@...esyslogic.com.tw,
        ben.chuang@...esyslogic.com.tw, Ben Chuang <benchuanggli@...il.com>
Subject: [PATCH] mmc: sdhci-pci-gli: A workaround to allow GL9755 enter ASPM L1.2

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

When GL9755 enters ASPM L1 sub-states, it will stay at L1.1 and will not
enter L1.2. The workaround is to toggle PM state to allow GL9755 to enter
ASPM L1.2.

Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
---
 drivers/mmc/host/sdhci-pci-gli.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/mmc/host/sdhci-pci-gli.c b/drivers/mmc/host/sdhci-pci-gli.c
index 97035d77c18c..52230857388f 100644
--- a/drivers/mmc/host/sdhci-pci-gli.c
+++ b/drivers/mmc/host/sdhci-pci-gli.c
@@ -137,6 +137,9 @@
 #define PCI_GLI_9755_SerDes  0x70
 #define PCI_GLI_9755_SCP_DIS   BIT(19)
 
+#define PCI_GLI_9755_PM_CTRL     0xFC
+#define   PCI_GLI_9755_PM_STATE    GENMASK(1, 0)
+
 #define GLI_MAX_TUNING_LOOP 40
 
 /* Genesys Logic chipset */
@@ -597,6 +600,13 @@ static void gl9755_hw_setting(struct sdhci_pci_slot *slot)
 			    GLI_9755_CFG2_L1DLY_VALUE);
 	pci_write_config_dword(pdev, PCI_GLI_9755_CFG2, value);
 
+	/* toggle PM state to allow GL9755 to enter ASPM L1.2 */
+	pci_read_config_dword(pdev, PCI_GLI_9755_PM_CTRL, &value);
+	value |= PCI_GLI_9755_PM_STATE;
+	pci_write_config_dword(pdev, PCI_GLI_9755_PM_CTRL, value);
+	value &= ~PCI_GLI_9755_PM_STATE;
+	pci_write_config_dword(pdev, PCI_GLI_9755_PM_CTRL, value);
+
 	gl9755_wt_off(pdev);
 }
 
-- 
2.35.1