[FYI 4/4] ARM: mmci: add support for double buffering

From: Per Forlin
Date: Wed Jan 12 2011 - 13:21:08 EST

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In reply to: Per Forlin: "[FYI 3/4] MMCI: Corrections for DMA"
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This is an example of how to utilize the double buffer
support in the mmc framework. This patch is not intended
nor ready for mainline.

Implement pre_req() and post_reg() hooks. pre_req()
runs dma_map_sg and prepares the dma descriptor and
post_req calls dma_unmap_sg.

Signed-off-by: Per Forlin <per.forlin@xxxxxxxxxx>
---
drivers/mmc/host/mmci.c | 164 ++++++++++++++++++++++++++++++++++++-----------
drivers/mmc/host/mmci.h | 4 +
2 files changed, 130 insertions(+), 38 deletions(-)

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index ab44f5f..7f0b12a 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -276,6 +276,7 @@ static void __devinit mmci_setup_dma(struct mmci_host *host)
host->dma_tx_channel = host->dma_rx_channel;
}
host->dma_enable = true;
+
dev_info(mmc_dev(host->mmc), "use DMA channels DMA RX %s, DMA TX %s\n",
dma_chan_name(host->dma_rx_channel),
dma_chan_name(host->dma_tx_channel));
@@ -296,11 +297,6 @@ static inline void mmci_disable_dma(struct mmci_host *host)

static void mmci_dma_data_end(struct mmci_host *host)
{
- struct mmc_data *data = host->data;
-
- dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
- (data->flags & MMC_DATA_WRITE)
- ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
host->dma_on_current_xfer = false;
}

@@ -353,7 +349,9 @@ static void mmci_dma_callback(void *arg)
spin_unlock_irqrestore(&host->lock, flags);
}

-static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
+static struct dma_async_tx_descriptor *mmci_dma_cfg(struct mmc_data *data,
+ struct mmci_host *host,
+ struct dma_chan **chan_dma)
{
struct variant_data *variant = host->variant;
struct dma_slave_config rx_conf = {
@@ -368,19 +366,13 @@ static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
.direction = DMA_TO_DEVICE,
.dst_maxburst = variant->fifohalfsize >> 2, /* # of words */
};
- struct mmc_data *data = host->data;
enum dma_data_direction direction;
struct dma_chan *chan;
struct dma_async_tx_descriptor *desc;
struct scatterlist *sg;
- dma_cookie_t cookie;
int i;
- unsigned int irqmask0;
int sg_len;

- datactrl |= MCI_DPSM_DMAENABLE;
- datactrl |= variant->dmareg_enable;
-
if (data->flags & MMC_DATA_READ) {
if (host->size <= variant->txsize_threshold)
rx_conf.src_maxburst = 1;
@@ -404,11 +396,12 @@ static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
dev_vdbg(mmc_dev(host->mmc), "MMCI SGlist %d dir %d: length: %08x\n",
i, direction, sg->length);
if (sg->offset & 3 || sg->length & 3)
- return -EINVAL;
+ return NULL;
}

sg_len = dma_map_sg(mmc_dev(host->mmc), data->sg,
- data->sg_len, direction);
+ data->sg_len, direction);
+
if (!sg_len)
goto map_err;

@@ -420,7 +413,42 @@ static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)

desc->callback = mmci_dma_callback;
desc->callback_param = host;
- host->dma_desc = desc;
+
+ *chan_dma = chan;
+ return desc;
+unmap_exit:
+ dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len, direction);
+map_err:
+ *chan_dma = NULL;
+ return NULL;
+}
+
+static void mmci_dma_prepare(struct mmc_data *data, struct mmci_host *host)
+{
+
+ if (data != host->data_next)
+ host->dma_desc = mmci_dma_cfg(data, host, &host->cur_chan);
+ else {
+ host->dma_desc = host->dma_desc_next;
+ host->cur_chan = host->next_chan;
+
+ host->dma_desc_next = NULL;
+ host->data_next = NULL;
+ host->next_chan = NULL;
+ }
+
+ BUG_ON(!host->dma_desc);
+ BUG_ON(!host->cur_chan);
+}
+
+static int mmci_dma_start_data(struct mmci_host *host)
+{
+ struct mmc_data *data = host->data;
+ struct dma_async_tx_descriptor *desc = host->dma_desc;
+ struct dma_chan *chan = host->cur_chan;
+ dma_cookie_t cookie;
+ enum dma_data_direction direction;
+
dev_vdbg(mmc_dev(host->mmc), "Submit MMCI DMA job, sglen %d "
"blksz %04x blks %04x flags %08x\n",
data->sg_len, data->blksz, data->blocks, data->flags);
@@ -433,6 +461,24 @@ static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
host->dma_on_current_xfer = true;
chan->device->device_issue_pending(chan);

+ return 0;
+unmap_exit:
+ if (data->flags & MMC_DATA_READ)
+ direction = DMA_FROM_DEVICE;
+
+ dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len, direction);
+ chan->device->device_control(chan, DMA_TERMINATE_ALL, 0);
+
+ return -ENOMEM;
+}
+
+static int mmci_dma_start_fifo(struct mmci_host *host, unsigned int datactrl)
+{
+ unsigned int irqmask0;
+
+ datactrl |= MCI_DPSM_DMAENABLE;
+ datactrl |= host->variant->dmareg_enable;
+
/*
* MMCI monitors both MCI_DATAEND and the DMA callback.
* Both events must occur before the transfer is considered
@@ -447,12 +493,45 @@ static int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
/* Trigger the DMA transfer */
writel(datactrl, host->base + MMCIDATACTRL);
return 0;
+}
+
+static void mmci_post_request(struct mmc_host *mmc, struct mmc_request *mrq)
+{
+ struct mmci_host *host = mmc_priv(mmc);
+ struct mmc_data *data = mrq->data;
+
+ if (host->dma_enable)
+ dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
+ (data->flags & MMC_DATA_WRITE)
+ ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
+}
+
+static void mmci_pre_request(struct mmc_host *mmc, struct mmc_request *mrq,
+ bool host_is_idle)
+{
+ struct mmci_host *host = mmc_priv(mmc);
+ struct mmc_data *data = mrq->data;
+
+ if (host->dma_enable && !host_is_idle) {
+ struct dma_async_tx_descriptor *desc;
+ struct dma_chan *chan;
+
+ desc = mmci_dma_cfg(data, host, &chan);
+ if (desc == NULL)
+ goto no_next;
+
+ host->dma_desc_next = desc;
+ host->data_next = data;
+ host->next_chan = chan;
+ }
+
+ return;
+
+ no_next:
+ host->dma_desc_next = NULL;
+ host->data_next = NULL;
+ host->next_chan = NULL;

-unmap_exit:
- dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len, direction);
-map_err:
- chan->device->device_control(chan, DMA_TERMINATE_ALL, 0);
- return -ENOMEM;
}
#else
/* Blank functions if the DMA engine is not available */
@@ -472,10 +551,23 @@ static inline void mmci_dma_terminate(struct mmci_host *host)
{
}

-static inline int mmci_dma_start_data(struct mmci_host *host, unsigned int datactrl)
+static inline int mmci_dma_start_data(struct mmci_host *host)
{
return -ENOSYS;
}
+
+static inline int mmci_dma_start_fifo(struct mmci_host *host,
+ unsigned int datactrl)
+{
+ return -ENOSYS;
+}
+
+static void mmci_dma_prepare(struct mmc_data *data, struct mmci_host *host)
+{
+}
+
+#define mmci_post_request NULL
+#define mmci_pre_request NULL
#endif

static void mmci_start_data(struct mmci_host *host, struct mmc_data *data)
@@ -519,7 +611,7 @@ static void mmci_start_data(struct mmci_host *host, struct mmc_data *data)
* Attempt to use DMA operation mode, if this
* should fail, fall back to PIO mode
*/
- ret = mmci_dma_start_data(host, datactrl);
+ ret = mmci_dma_start_fifo(host, datactrl);
if (!ret)
return;
}
@@ -662,13 +754,6 @@ mmci_data_irq(struct mmci_host *host, struct mmc_data *data,
mmci_stop_data(host);
host->dataend = false;

- /*
- * Variants with broken blockend flags need to handle
- * the end of the entire transfer here.
- */
- if (variant->broken_blockend && !data->error)
- host->data_xfered += data->blksz * data->blocks;
-
if (!data->stop)
mmci_request_end(host, data->mrq);
else
@@ -705,6 +790,8 @@ mmci_cmd_irq(struct mmci_host *host, struct mmc_command *cmd,
mmci_request_end(host, cmd->mrq);
} else if (!(cmd->data->flags & MMC_DATA_READ)) {
mmci_start_data(host, cmd->data);
+ if (host->dma_enable)
+ mmci_dma_start_data(host);
}
}

@@ -944,6 +1031,13 @@ static void mmci_request(struct mmc_host *mmc, struct mmc_request *mrq)

mmci_start_command(host, mrq->cmd, 0);

+ if (host->dma_enable && mrq->data) {
+ mmci_dma_prepare(mrq->data, host);
+
+ if (mrq->data->flags & MMC_DATA_READ)
+ mmci_dma_start_data(host);
+ }
+
spin_unlock_irqrestore(&host->lock, flags);
}

@@ -1053,6 +1147,8 @@ static irqreturn_t mmci_cd_irq(int irq, void *dev_id)

static const struct mmc_host_ops mmci_ops = {
.request = mmci_request,
+ .pre_req = mmci_pre_request,
+ .post_req = mmci_post_request,
.set_ios = mmci_set_ios,
.get_ro = mmci_get_ro,
.get_cd = mmci_get_cd,
@@ -1180,15 +1276,7 @@ static int __devinit mmci_probe(struct amba_device *dev, struct amba_id *id)
* single request.
*/
mmc->max_req_size = (1 << variant->datalength_bits) - 1;
-
- /*
- * Set the maximum segment size. Right now DMA sets the
- * limit and not the data length register. Thus until the DMA
- * driver not handles this, the segment size is limited by DMA.
- * DMA limit: src_addr_width x (64 KB -1). src_addr_width
- * can be 1.
- */
- mmc->max_seg_size = 65535;
+ mmc->max_seg_size = mmc->max_req_size;

/*
* Block size can be up to 2048 bytes, but must be a power of two.
diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
index 39b7ac7..828ab5a 100644
--- a/drivers/mmc/host/mmci.h
+++ b/drivers/mmc/host/mmci.h
@@ -196,6 +196,10 @@ struct mmci_host {
struct dma_chan *dma_rx_channel;
struct dma_chan *dma_tx_channel;
struct dma_async_tx_descriptor *dma_desc;
+ struct dma_async_tx_descriptor *dma_desc_next;
+ struct mmc_data *data_next;
+ struct dma_chan *cur_chan;
+ struct dma_chan *next_chan;
#endif
};

--
1.7.1

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Next message: Sebastian Andrzej Siewior: "Re: [PATCH v2 07/15] of: move of_irq_map_pci() into generic code"
Previous message: Glen Duncan: "Re: What has become of IPFC in Linux?"
In reply to: Per Forlin: "[FYI 3/4] MMCI: Corrections for DMA"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]