So far a bounce buffer is used to serialize the scatterlist(s).
This overhead can be avoided by switching to descriptor chain mode.
As result the performance is drastically improved. On a Odroid-C2 with
a 128 GB eMMC module raw reads reach 140 MB/s.
Prerequisite for descriptor chain mode is that all scatterlist buffers
are 8 byte aligned for 64-bit DMA. That's not always the case, at least
the brcmfmac SDIO WiFi driver is known to cause problems.
Therefore, for each request, check upfront whether all scatterlist
buffers are 8 byte aligned and fall back to bounce buffer mode if
that's not the case.
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
---
drivers/mmc/host/meson-gx-mmc.c | 172 ++++++++++++++++++++++++++++++++++++----
1 file changed, 156 insertions(+), 16 deletions(-)
diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index eb5ee68d..1842ed34 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c
@@ -111,6 +111,11 @@
#define SD_EMMC_CMD_TIMEOUT 1024 /* in ms */
#define SD_EMMC_CMD_TIMEOUT_DATA 4096 /* in ms */
#define SD_EMMC_CFG_CMD_GAP 16 /* in clock cycles */
+#define SD_EMMC_DESC_BUF_LEN PAGE_SIZE
+
+#define SD_EMMC_PRE_REQ_DONE BIT(0)
+#define SD_EMMC_DESC_CHAIN_MODE BIT(1)
+
#define MUX_CLK_NUM_PARENTS 2
struct meson_tuning_params {
@@ -119,6 +124,13 @@ struct meson_tuning_params {
u8 rx_phase;
};
+struct sd_emmc_desc {
+ u32 cmd_cfg;
+ u32 cmd_arg;
+ u32 cmd_data;
+ u32 cmd_resp;
+};
+
struct meson_host {
struct device *dev;
struct mmc_host *mmc;
@@ -137,18 +149,13 @@ struct meson_host {
unsigned int bounce_buf_size;
void *bounce_buf;
dma_addr_t bounce_dma_addr;
+ struct sd_emmc_desc *descs;
+ dma_addr_t descs_dma_addr;
struct meson_tuning_params tp;
bool vqmmc_enabled;
};
-struct sd_emmc_desc {
- u32 cmd_cfg;
- u32 cmd_arg;
- u32 cmd_data;
- u32 cmd_resp;
-};
-
#define CMD_CFG_LENGTH_MASK GENMASK(8, 0)
#define CMD_CFG_BLOCK_MODE BIT(9)
#define CMD_CFG_R1B BIT(10)
@@ -195,6 +202,66 @@ static struct mmc_command *meson_mmc_get_next_command(struct mmc_command *cmd)
return NULL;
}
+static void meson_mmc_get_transfer_mode(struct mmc_host *mmc,
+ struct mmc_request *mrq)
+{
+ struct mmc_data *data = mrq->data;
+ struct scatterlist *sg;
+ int i;
+ bool use_desc_chain_mode = true;
+
+ for_each_sg(data->sg, sg, data->sg_len, i)
+ /* check for 8 byte alignment */
+ if (sg->offset & 7) {
+ WARN_ONCE(1, "unaligned scatterlist buffer\n");
+ use_desc_chain_mode = false;
+ break;
+ }
+
+ if (use_desc_chain_mode)
+ data->host_cookie |= SD_EMMC_DESC_CHAIN_MODE;
+}
+
+static inline bool meson_mmc_desc_chain_mode(const struct mmc_data *data)
+{
+ return data->host_cookie & SD_EMMC_DESC_CHAIN_MODE;
+}
+
+static inline bool meson_mmc_bounce_buf_read(const struct mmc_data *data)
+{
+ return data && data->flags & MMC_DATA_READ &&
+ !meson_mmc_desc_chain_mode(data);
+}
+
+static void meson_mmc_pre_req(struct mmc_host *mmc, struct mmc_request *mrq)
+{
+ struct mmc_data *data = mrq->data;
+
+ if (!data)
+ return;
+
+ meson_mmc_get_transfer_mode(mmc, mrq);
+ data->host_cookie |= SD_EMMC_PRE_REQ_DONE;
+
+ if (!meson_mmc_desc_chain_mode(data))
+ return;
+
+ data->sg_count = dma_map_sg(mmc_dev(mmc), data->sg, data->sg_len,
+ mmc_get_dma_dir(data));
+ if (!data->sg_count)
+ dev_err(mmc_dev(mmc), "dma_map_sg failed");
+}
+
+static void meson_mmc_post_req(struct mmc_host *mmc, struct mmc_request *mrq,
+ int err)
+{
+ struct mmc_data *data = mrq->data;
+
+ if (data && meson_mmc_desc_chain_mode(data) && data->sg_count)
+ dma_unmap_sg(mmc_dev(mmc), data->sg, data->sg_len,
+ mmc_get_dma_dir(data));
+}
+
static int meson_mmc_clk_set(struct meson_host *host, unsigned long clk_rate)
{
struct mmc_host *mmc = host->mmc;
@@ -509,6 +576,44 @@ static void meson_mmc_set_response_bits(struct mmc_command *cmd, u32 *cmd_cfg)
}
}
+static void meson_mmc_desc_chain_transfer(struct mmc_host *mmc, u32 cmd_cfg)
+{
+ struct meson_host *host = mmc_priv(mmc);
+ struct sd_emmc_desc *desc = host->descs;
+ struct mmc_data *data = host->cmd->data;
+ struct scatterlist *sg;
+ u32 start;
+ int i;
+
+ if (data->flags & MMC_DATA_WRITE)
+ cmd_cfg |= CMD_CFG_DATA_WR;
+
+ if (data->blocks > 1) {
+ cmd_cfg |= CMD_CFG_BLOCK_MODE;
+ meson_mmc_set_blksz(mmc, data->blksz);
+ }
+
+ for_each_sg(data->sg, sg, data->sg_count, i) {
+ unsigned int len = sg_dma_len(sg);
+
+ if (data->blocks > 1)
+ len /= data->blksz;
+
+ desc[i].cmd_cfg = cmd_cfg;
+ desc[i].cmd_cfg |= FIELD_PREP(CMD_CFG_LENGTH_MASK, len);
+ if (i > 0)
+ desc[i].cmd_cfg |= CMD_CFG_NO_CMD;
+ desc[i].cmd_arg = host->cmd->arg;
+ desc[i].cmd_resp = 0;
+ desc[i].cmd_data = sg_dma_address(sg);
+ }
+ desc[data->sg_count - 1].cmd_cfg |= CMD_CFG_END_OF_CHAIN;
+
+ dma_wmb(); /* ensure descriptor is written before kicked */
+ start = host->descs_dma_addr | START_DESC_BUSY;
+ writel(start, host->regs + SD_EMMC_START);
+}
+
static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
{
struct meson_host *host = mmc_priv(mmc);
@@ -519,6 +624,8 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
/* Setup descriptors */
dma_rmb();
+ host->cmd = cmd;
+
cmd_cfg |= FIELD_PREP(CMD_CFG_CMD_INDEX_MASK, cmd->opcode);
cmd_cfg |= CMD_CFG_OWNER; /* owned by CPU */
@@ -526,10 +633,16 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
/* data? */
if (data) {
+ data->bytes_xfered = 0;
cmd_cfg |= CMD_CFG_DATA_IO;
cmd_cfg |= FIELD_PREP(CMD_CFG_TIMEOUT_MASK,
ilog2(meson_mmc_get_timeout_msecs(data)));
+ if (meson_mmc_desc_chain_mode(data)) {
+ meson_mmc_desc_chain_transfer(mmc, cmd_cfg);
+ return;
+ }
+
if (data->blocks > 1) {
cmd_cfg |= CMD_CFG_BLOCK_MODE;
cmd_cfg |= FIELD_PREP(CMD_CFG_LENGTH_MASK,
@@ -539,7 +652,6 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
cmd_cfg |= FIELD_PREP(CMD_CFG_LENGTH_MASK, data->blksz);
}
- data->bytes_xfered = 0;
xfer_bytes = data->blksz * data->blocks;
if (data->flags & MMC_DATA_WRITE) {
cmd_cfg |= CMD_CFG_DATA_WR;
@@ -555,8 +667,6 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
ilog2(SD_EMMC_CMD_TIMEOUT));
}
- host->cmd = cmd;
-
/* Last descriptor */
cmd_cfg |= CMD_CFG_END_OF_CHAIN;
writel(cmd_cfg, host->regs + SD_EMMC_CMD_CFG);
@@ -569,14 +679,25 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
static void meson_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
{
struct meson_host *host = mmc_priv(mmc);
+ bool needs_pre_post_req = mrq->data &&
+ !(mrq->data->host_cookie & SD_EMMC_PRE_REQ_DONE);
+
+ if (needs_pre_post_req) {
+ meson_mmc_get_transfer_mode(mmc, mrq);
+ if (!meson_mmc_desc_chain_mode(mrq->data))
+ needs_pre_post_req = false;
+ }
+
+ if (needs_pre_post_req)
+ meson_mmc_pre_req(mmc, mrq);
/* Stop execution */
writel(0, host->regs + SD_EMMC_START);
- if (mrq->sbc)
- meson_mmc_start_cmd(mmc, mrq->sbc);
- else
- meson_mmc_start_cmd(mmc, mrq->cmd);
+ meson_mmc_start_cmd(mmc, mrq->sbc ?: mrq->cmd);
+
+ if (needs_pre_post_req)
+ meson_mmc_post_req(mmc, mrq, 0);
}
static void meson_mmc_read_resp(struct mmc_host *mmc, struct mmc_command *cmd)
@@ -654,7 +775,9 @@ static irqreturn_t meson_mmc_irq(int irq, void *dev_id)
if (status & (IRQ_END_OF_CHAIN | IRQ_RESP_STATUS)) {
if (data && !cmd->error)
data->bytes_xfered = data->blksz * data->blocks;
- ret = IRQ_WAKE_THREAD;
+ if (meson_mmc_bounce_buf_read(data) ||
+ meson_mmc_get_next_command(cmd))
+ ret = IRQ_WAKE_THREAD;
} else {
dev_warn(host->dev, "Unknown IRQ! status=0x%04x: MMC CMD%u arg=0x%08x flags=0x%08x stop=%d\n",
status, cmd->opcode, cmd->arg,
@@ -691,7 +814,7 @@ static irqreturn_t meson_mmc_irq_thread(int irq, void *dev_id)
return IRQ_NONE;
data = cmd->data;
- if (data && data->flags & MMC_DATA_READ) {
+ if (meson_mmc_bounce_buf_read(data)) {
xfer_bytes = data->blksz * data->blocks;
WARN_ON(xfer_bytes > host->bounce_buf_size);
sg_copy_from_buffer(data->sg, data->sg_len,
@@ -760,6 +883,8 @@ static const struct mmc_host_ops meson_mmc_ops = {
.request = meson_mmc_request,
.set_ios = meson_mmc_set_ios,
.get_cd = meson_mmc_get_cd,
+ .pre_req = meson_mmc_pre_req,
+ .post_req = meson_mmc_post_req,
.execute_tuning = meson_mmc_execute_tuning,
};
@@ -845,6 +970,8 @@ static int meson_mmc_probe(struct platform_device *pdev)
mmc->caps |= MMC_CAP_CMD23;
mmc->max_blk_count = CMD_CFG_LENGTH_MASK;
mmc->max_req_size = mmc->max_blk_count * mmc->max_blk_size;
+ mmc->max_segs = SD_EMMC_DESC_BUF_LEN / sizeof(struct sd_emmc_desc);
+ mmc->max_seg_size = mmc->max_req_size;
/* data bounce buffer */
host->bounce_buf_size = mmc->max_req_size;
@@ -857,11 +984,22 @@ static int meson_mmc_probe(struct platform_device *pdev)
goto err_div_clk;
}
+ host->descs = dma_alloc_coherent(host->dev, SD_EMMC_DESC_BUF_LEN,
+ &host->descs_dma_addr, GFP_KERNEL);
+ if (!host->descs) {
+ dev_err(host->dev, "Allocating descriptor DMA buffer failed\n");
+ ret = -ENOMEM;
+ goto err_bounce_buf;
+ }
+
mmc->ops = &meson_mmc_ops;
mmc_add_host(mmc);
return 0;
+err_bounce_buf:
+ dma_free_coherent(host->dev, host->bounce_buf_size,
+ host->bounce_buf, host->bounce_dma_addr);
err_div_clk:
clk_disable_unprepare(host->cfg_div_clk);
err_core_clk:
@@ -880,6 +1018,8 @@ static int meson_mmc_remove(struct platform_device *pdev)
/* disable interrupts */
writel(0, host->regs + SD_EMMC_IRQ_EN);
+ dma_free_coherent(host->dev, SD_EMMC_DESC_BUF_LEN,
+ host->descs, host->descs_dma_addr);
dma_free_coherent(host->dev, host->bounce_buf_size,
host->bounce_buf, host->bounce_dma_addr);
--
2.12.2
--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
