mmc: sdhci-pci-gli: A workaround to allow GL9750 to enter ASPM L1.2

When GL9750 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 GL9750 to enter
ASPM L1.2.
Signed-off-by: Victor Shih <victor.shih@genesyslogic.com.tw>
Link: https://lore.kernel.org/r/20230912091710.7797-1-victorshihgli@gmail.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-pci-gli.c

@@ -25,6 +25,9 @@
 #define   GLI_9750_WT_EN_ON	    0x1
 #define   GLI_9750_WT_EN_OFF	    0x0
 
+#define PCI_GLI_9750_PM_CTRL	0xFC
+#define   PCI_GLI_9750_PM_STATE	  GENMASK(1, 0)
+
 #define SDHCI_GLI_9750_CFG2          0x848
 #define   SDHCI_GLI_9750_CFG2_L1DLY    GENMASK(28, 24)
 #define   GLI_9750_CFG2_L1DLY_VALUE    0x1F
@@ -536,8 +539,12 @@ static void sdhci_gl9750_set_clock(struct sdhci_host *host, unsigned int clock)
 
 static void gl9750_hw_setting(struct sdhci_host *host)
 {
+	struct sdhci_pci_slot *slot = sdhci_priv(host);
+	struct pci_dev *pdev;
 	u32 value;
 
+	pdev = slot->chip->pdev;
+
 	gl9750_wt_on(host);
 
 	value = sdhci_readl(host, SDHCI_GLI_9750_CFG2);
@@ -547,6 +554,13 @@ static void gl9750_hw_setting(struct sdhci_host *host)
 			    GLI_9750_CFG2_L1DLY_VALUE);
 	sdhci_writel(host, value, SDHCI_GLI_9750_CFG2);
 
+	/* toggle PM state to allow GL9750 to enter ASPM L1.2 */
+	pci_read_config_dword(pdev, PCI_GLI_9750_PM_CTRL, &value);
+	value |= PCI_GLI_9750_PM_STATE;
+	pci_write_config_dword(pdev, PCI_GLI_9750_PM_CTRL, value);
+	value &= ~PCI_GLI_9750_PM_STATE;
+	pci_write_config_dword(pdev, PCI_GLI_9750_PM_CTRL, value);
+
 	gl9750_wt_off(host);
 }