mmc: dw_mmc: adjust the fifoth with block size

This change helps to choose msize, rx_watermark and tx_watermark
depending on block size for IDMAC mode.  For SDIO block size can be
variable, so if these values are set incorrectly, card clock may stop.
Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/dw_mmc.c

@@ -529,6 +529,47 @@ static void dw_mci_post_req(struct mmc_host *mmc,
 	data->host_cookie = 0;
 }
 
+static void dw_mci_adjust_fifoth(struct dw_mci *host, struct mmc_data *data)
+{
+#ifdef CONFIG_MMC_DW_IDMAC
+	unsigned int blksz = data->blksz;
+	const u32 mszs[] = {1, 4, 8, 16, 32, 64, 128, 256};
+	u32 fifo_width = 1 << host->data_shift;
+	u32 blksz_depth = blksz / fifo_width, fifoth_val;
+	u32 msize = 0, rx_wmark = 1, tx_wmark, tx_wmark_invers;
+	int idx = (sizeof(mszs) / sizeof(mszs[0])) - 1;
+
+	tx_wmark = (host->fifo_depth) / 2;
+	tx_wmark_invers = host->fifo_depth - tx_wmark;
+
+	/*
+	 * MSIZE is '1',
+	 * if blksz is not a multiple of the FIFO width
+	 */
+	if (blksz % fifo_width) {
+		msize = 0;
+		rx_wmark = 1;
+		goto done;
+	}
+
+	do {
+		if (!((blksz_depth % mszs[idx]) ||
+		     (tx_wmark_invers % mszs[idx]))) {
+			msize = idx;
+			rx_wmark = mszs[idx] - 1;
+			break;
+		}
+	} while (--idx > 0);
+	/*
+	 * If idx is '0', it won't be tried
+	 * Thus, initial values are uesed
+	 */
+done:
+	fifoth_val = SDMMC_SET_FIFOTH(msize, rx_wmark, tx_wmark);
+	mci_writel(host, FIFOTH, fifoth_val);
+#endif
+}
+
 static int dw_mci_submit_data_dma(struct dw_mci *host, struct mmc_data *data)
 {
 	int sg_len;
@@ -553,6 +594,14 @@ static int dw_mci_submit_data_dma(struct dw_mci *host, struct mmc_data *data)
 		 (unsigned long)host->sg_cpu, (unsigned long)host->sg_dma,
 		 sg_len);
 
+	/*
+	 * Decide the MSIZE and RX/TX Watermark.
+	 * If current block size is same with previous size,
+	 * no need to update fifoth.
+	 */
+	if (host->prev_blksz != data->blksz)
+		dw_mci_adjust_fifoth(host, data);
+
 	/* Enable the DMA interface */
 	temp = mci_readl(host, CTRL);
 	temp |= SDMMC_CTRL_DMA_ENABLE;
@@ -603,6 +652,21 @@ static void dw_mci_submit_data(struct dw_mci *host, struct mmc_data *data)
 		temp = mci_readl(host, CTRL);
 		temp &= ~SDMMC_CTRL_DMA_ENABLE;
 		mci_writel(host, CTRL, temp);
+
+		/*
+		 * Use the initial fifoth_val for PIO mode.
+		 * If next issued data may be transfered by DMA mode,
+		 * prev_blksz should be invalidated.
+		 */
+		mci_writel(host, FIFOTH, host->fifoth_val);
+		host->prev_blksz = 0;
+	} else {
+		/*
+		 * Keep the current block size.
+		 * It will be used to decide whether to update
+		 * fifoth register next time.
+		 */
+		host->prev_blksz = data->blksz;
 	}
 }
 
@@ -2368,8 +2432,8 @@ int dw_mci_probe(struct dw_mci *host)
 		fifo_size = host->pdata->fifo_depth;
 	}
 	host->fifo_depth = fifo_size;
-	host->fifoth_val = ((0x2 << 28) | ((fifo_size/2 - 1) << 16) |
-			((fifo_size/2) << 0));
+	host->fifoth_val =
+		SDMMC_SET_FIFOTH(0x2, fifo_size / 2 - 1, fifo_size / 2);
 	mci_writel(host, FIFOTH, host->fifoth_val);
 
 	/* disable clock to CIU */
@@ -2552,8 +2616,12 @@ int dw_mci_resume(struct dw_mci *host)
 	if (host->use_dma && host->dma_ops->init)
 		host->dma_ops->init(host);
 
-	/* Restore the old value at FIFOTH register */
+	/*
+	 * Restore the initial value at FIFOTH register
+	 * And Invalidate the prev_blksz with zero
+	 */
 	mci_writel(host, FIFOTH, host->fifoth_val);
+	host->prev_blksz = 0;
 
 	/* Put in max timeout */
 	mci_writel(host, TMOUT, 0xFFFFFFFF);

drivers/mmc/host/dw_mmc.h

@@ -128,6 +128,10 @@
 #define SDMMC_CMD_INDX(n)		((n) & 0x1F)
 /* Status register defines */
 #define SDMMC_GET_FCNT(x)		(((x)>>17) & 0x1FFF)
+/* FIFOTH register defines */
+#define SDMMC_SET_FIFOTH(m, r, t)	(((m) & 0x7) << 28 | \
+					 ((r) & 0xFFF) << 16 | \
+					 ((t) & 0xFFF))
 /* Internal DMAC interrupt defines */
 #define SDMMC_IDMAC_INT_AI		BIT(9)
 #define SDMMC_IDMAC_INT_NI		BIT(8)

include/linux/mmc/dw_mmc.h

@@ -129,6 +129,7 @@ struct dw_mci {
 	struct mmc_request	*mrq;
 	struct mmc_command	*cmd;
 	struct mmc_data		*data;
+	unsigned int		prev_blksz;
 	struct workqueue_struct	*card_workqueue;
 
 	/* DMA interface members*/