Skip to content

Commit

Permalink
mtd: rawnand: qcom: wait for desc completion in all BAM channels
Browse files Browse the repository at this point in the history
commit 6f20070 upstream.

The BAM has 3 channels - tx, rx and command. command channel
is used for register read/writes, tx channel for data writes
and rx channel for data reads. Currently, the driver assumes the
transfer completion once it gets all the command descriptors
completed. Sometimes, there is race condition between data channel
(tx/rx) and command channel completion. In these cases,
the data present in buffer is not valid during small window
between command descriptor completion and data descriptor
completion.

This patch generates NAND transfer completion when both
(Data and Command) DMA channels have completed all its DMA
descriptors. It assigns completion callback in last
DMA descriptors of that channel and wait for completion.

Fixes: 8d6b6d7 ("mtd: nand: qcom: support for command descriptor formation")
Cc: stable@vger.kernel.org
Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  • Loading branch information
Abhishek Sahu authored and Greg Kroah-Hartman committed Sep 5, 2018
1 parent 21ab602 commit f905fc1
Showing 1 changed file with 52 additions and 1 deletion.
53 changes: 52 additions & 1 deletion drivers/mtd/nand/raw/qcom_nandc.c
Original file line number Diff line number Diff line change
Expand Up @@ -213,6 +213,8 @@ nandc_set_reg(nandc, NAND_READ_LOCATION_##reg, \
#define QPIC_PER_CW_CMD_SGL 32
#define QPIC_PER_CW_DATA_SGL 8

#define QPIC_NAND_COMPLETION_TIMEOUT msecs_to_jiffies(2000)

/*
* Flags used in DMA descriptor preparation helper functions
* (i.e. read_reg_dma/write_reg_dma/read_data_dma/write_data_dma)
Expand Down Expand Up @@ -245,6 +247,11 @@ nandc_set_reg(nandc, NAND_READ_LOCATION_##reg, \
* @tx_sgl_start - start index in data sgl for tx.
* @rx_sgl_pos - current index in data sgl for rx.
* @rx_sgl_start - start index in data sgl for rx.
* @wait_second_completion - wait for second DMA desc completion before making
* the NAND transfer completion.
* @txn_done - completion for NAND transfer.
* @last_data_desc - last DMA desc in data channel (tx/rx).
* @last_cmd_desc - last DMA desc in command channel.
*/
struct bam_transaction {
struct bam_cmd_element *bam_ce;
Expand All @@ -258,6 +265,10 @@ struct bam_transaction {
u32 tx_sgl_start;
u32 rx_sgl_pos;
u32 rx_sgl_start;
bool wait_second_completion;
struct completion txn_done;
struct dma_async_tx_descriptor *last_data_desc;
struct dma_async_tx_descriptor *last_cmd_desc;
};

/*
Expand Down Expand Up @@ -504,6 +515,8 @@ alloc_bam_transaction(struct qcom_nand_controller *nandc)

bam_txn->data_sgl = bam_txn_buf;

init_completion(&bam_txn->txn_done);

return bam_txn;
}

Expand All @@ -523,11 +536,33 @@ static void clear_bam_transaction(struct qcom_nand_controller *nandc)
bam_txn->tx_sgl_start = 0;
bam_txn->rx_sgl_pos = 0;
bam_txn->rx_sgl_start = 0;
bam_txn->last_data_desc = NULL;
bam_txn->wait_second_completion = false;

sg_init_table(bam_txn->cmd_sgl, nandc->max_cwperpage *
QPIC_PER_CW_CMD_SGL);
sg_init_table(bam_txn->data_sgl, nandc->max_cwperpage *
QPIC_PER_CW_DATA_SGL);

reinit_completion(&bam_txn->txn_done);
}

/* Callback for DMA descriptor completion */
static void qpic_bam_dma_done(void *data)
{
struct bam_transaction *bam_txn = data;

/*
* In case of data transfer with NAND, 2 callbacks will be generated.
* One for command channel and another one for data channel.
* If current transaction has data descriptors
* (i.e. wait_second_completion is true), then set this to false
* and wait for second DMA descriptor completion.
*/
if (bam_txn->wait_second_completion)
bam_txn->wait_second_completion = false;
else
complete(&bam_txn->txn_done);
}

static inline struct qcom_nand_host *to_qcom_nand_host(struct nand_chip *chip)
Expand Down Expand Up @@ -756,6 +791,12 @@ static int prepare_bam_async_desc(struct qcom_nand_controller *nandc,

desc->dma_desc = dma_desc;

/* update last data/command descriptor */
if (chan == nandc->cmd_chan)
bam_txn->last_cmd_desc = dma_desc;
else
bam_txn->last_data_desc = dma_desc;

list_add_tail(&desc->node, &nandc->desc_list);

return 0;
Expand Down Expand Up @@ -1273,10 +1314,20 @@ static int submit_descs(struct qcom_nand_controller *nandc)
cookie = dmaengine_submit(desc->dma_desc);

if (nandc->props->is_bam) {
bam_txn->last_cmd_desc->callback = qpic_bam_dma_done;
bam_txn->last_cmd_desc->callback_param = bam_txn;
if (bam_txn->last_data_desc) {
bam_txn->last_data_desc->callback = qpic_bam_dma_done;
bam_txn->last_data_desc->callback_param = bam_txn;
bam_txn->wait_second_completion = true;
}

dma_async_issue_pending(nandc->tx_chan);
dma_async_issue_pending(nandc->rx_chan);
dma_async_issue_pending(nandc->cmd_chan);

if (dma_sync_wait(nandc->cmd_chan, cookie) != DMA_COMPLETE)
if (!wait_for_completion_timeout(&bam_txn->txn_done,
QPIC_NAND_COMPLETION_TIMEOUT))
return -ETIMEDOUT;
} else {
if (dma_sync_wait(nandc->chan, cookie) != DMA_COMPLETE)
Expand Down

0 comments on commit f905fc1

Please sign in to comment.