1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 02145e9697a9..1196f61a4ab6 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -2758,6 +2758,29 @@ static void ricoh_mmc_fixup_r5c832(struct pci_dev *dev)
 
         dev_notice(&dev->dev, "proprietary Ricoh MMC controller disabled (via firewire function)\n");
         dev_notice(&dev->dev, "MMC cards are now supported by standard SDHCI controller\n");
+
+        /*
+         * RICOH 0xe823 SD/MMC card reader fails to recognize
+         * certain types of SD/MMC cards. Lowering the SD base
+         * clock frequency from 200Mhz to 50Mhz fixes this issue.
+         *
+         * 0x150 - SD2.0 mode enable for changing base clock
+         *         frequency to 50Mhz
+         * 0xe1  - Base clock frequency
+         * 0x32  - 50Mhz new clock frequency
+         * 0xf9  - Key register for 0x150
+         * 0xfc  - key register for 0xe1
+         */
+        if (dev->device == PCI_DEVICE_ID_RICOH_R5CE823) {
+                pci_write_config_byte(dev, 0xf9, 0xfc);
+                pci_write_config_byte(dev, 0x150, 0x10);
+                pci_write_config_byte(dev, 0xf9, 0x00);
+                pci_write_config_byte(dev, 0xfc, 0x01);
+                pci_write_config_byte(dev, 0xe1, 0x32);
+                pci_write_config_byte(dev, 0xfc, 0x00);
+
+                dev_notice(&dev->dev, "MMC controller base frequency changed to 50Mhz.\n");
+        }
 }
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_RICOH, PCI_DEVICE_ID_RICOH_R5C832, ricoh_mmc_fixup_r5c832);
 DECLARE_PCI_FIXUP_RESUME_EARLY(PCI_VENDOR_ID_RICOH, PCI_DEVICE_ID_RICOH_R5C832, ricoh_mmc_fixup_r5c832);