mmc: sdhci-pci-gli: fix GL9750 DMA write corruption

The GL9750 SD host controller has intermittent data corruption during
DMA write operations. The GM_BURST register's R_OSRC_Lmt field
(bits 17:16), which limits outstanding DMA read requests from system
memory, is not being cleared during initialization. The Windows driver
sets R_OSRC_Lmt to zero, limiting requests to the smallest unit.

Clear R_OSRC_Lmt to match the Windows driver behavior. This eliminates
write corruption verified with f3write/f3read tests while maintaining
DMA performance.

Cc: [e-mail]
Fixes: e51df6ce668a ("mmc: host: sdhci-pci: Add Genesys Logic GL975x support")
Closes: https://lore.kernel.org/linux-mmc/[e-mail]/
Acked-by: Adrian Hunter <[e-mail]>
Signed-off-by: Matthew Schwartz <[e-mail]>
Reviewed-by: Ben Chuang <[e-mail]>
Signed-off-by: Ulf Hansson <[e-mail]>

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

···
 #define   GLI_9750_MISC_TX1_DLY_VALUE    0x5
 #define   SDHCI_GLI_9750_MISC_SSC_OFF    BIT(26)
 
+#define SDHCI_GLI_9750_GM_BURST_SIZE		  0x510
+#define   SDHCI_GLI_9750_GM_BURST_SIZE_R_OSRC_LMT  GENMASK(17, 16)
+
 #define SDHCI_GLI_9750_TUNING_CONTROL	          0x540
 #define   SDHCI_GLI_9750_TUNING_CONTROL_EN          BIT(4)
 #define   GLI_9750_TUNING_CONTROL_EN_ON             0x1
···
 	u32 misc_value;
 	u32 parameter_value;
 	u32 control_value;
+	u32 burst_value;
 	u16 ctrl2;
 
 	gl9750_wt_on(host);
+
+	/* clear R_OSRC_Lmt to avoid DMA write corruption */
+	burst_value = sdhci_readl(host, SDHCI_GLI_9750_GM_BURST_SIZE);
+	burst_value &= ~SDHCI_GLI_9750_GM_BURST_SIZE_R_OSRC_LMT;
+	sdhci_writel(host, burst_value, SDHCI_GLI_9750_GM_BURST_SIZE);
 
 	driving_value = sdhci_readl(host, SDHCI_GLI_9750_DRIVING);
 	pll_value = sdhci_readl(host, SDHCI_GLI_9750_PLL);