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Subject[PATCH v2 2/2] mxs-dma : rewrite the last parameter of mxs_dma_prep_slave_sg()
Date
[1] Background :
The GPMI does ECC read page operation with a DMA chain consist of three DMA
Command Structures. The middle one of the chain is used to enable the BCH,
and read out the NAND page.

The WAIT4END(wait for command end) is a comunication signal between
the GPMI and MXS-DMA.

[2] The current DMA code sets the WAIT4END bit at the last one, such as:

+-----+ +-----+ +-----+
| cmd | ------------> | cmd | ------------------> | cmd |
+-----+ +-----+ +-----+
^
|
|
set WAIT4END here

This chain works fine in the mx23/mx28.

[3] But in the new GPMI version (used in MX50/MX60), the WAIT4END bit should
be set not only at the last DMA Command Structure,
but also at the middle one, such as:

+-----+ +-----+ +-----+
| cmd | ------------> | cmd | ------------------> | cmd |
+-----+ +-----+ +-----+
^ ^
| |
| |
set WAIT4END here too set WAIT4END here

If we do not set WAIT4END, the BCH maybe stalls in "ECC reading page" state.
In the next ECC write page operation, a DMA-timeout occurs.
This has been catched in the MX6Q board.

[4] In order to fix the bug, rewrite the last parameter of mxs_dma_prep_slave_sg(),
and use the dma_ctrl_flags:
---------------------------------------------------------
DMA_PREP_INTERRUPT : append a new DMA Command Structrue.
DMA_CTRL_ACK : set the WAIT4END bit for this DMA Command Structure.
---------------------------------------------------------

[5] changes to the relative drivers:
<1> For mxs-mmc driver, just use the new flags, do not change any logic.
<2> For gpmi-nand driver, add new field `gpmi_version` to distinguish
different gpmi versions, and use the new flags.

Signed-off-by: Huang Shijie <b32955@freescale.com>
---
drivers/dma/mxs-dma.c | 32 ++++++++++++++++++++++++++++----
drivers/mmc/host/mxs-mmc.c | 10 +++++-----
drivers/mtd/nand/gpmi-nand/gpmi-lib.c | 28 ++++++++++++++++++++++------
drivers/mtd/nand/gpmi-nand/gpmi-nand.h | 4 ++++
drivers/mtd/nand/gpmi-nand/gpmi-regs.h | 2 ++
5 files changed, 61 insertions(+), 15 deletions(-)

diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c
index c80fbed..7d7498b 100644
--- a/drivers/dma/mxs-dma.c
+++ b/drivers/dma/mxs-dma.c
@@ -349,10 +349,32 @@ static void mxs_dma_free_chan_resources(struct dma_chan *chan)
clk_disable_unprepare(mxs_dma->clk);
}

+/*
+ * How to use the flags for ->device_prep_slave_sg() :
+ * [1] If there is only one DMA command in the DMA chain, the code should be:
+ * ......
+ * ->device_prep_slave_sg(DMA_CTRL_ACK);
+ * ......
+ * [2] If there are two DMA commands in the DMA chain, the code should be
+ * ......
+ * ->device_prep_slave_sg(0);
+ * ......
+ * ->device_prep_slave_sg(DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ * ......
+ * [3] If there are more than two DMA commands in the DMA chain, the code
+ * should be:
+ * ......
+ * ->device_prep_slave_sg(0); // First
+ * ......
+ * ->device_prep_slave_sg(DMA_PREP_INTERRUPT [| DMA_CTRL_ACK]);
+ * ......
+ * ->device_prep_slave_sg(DMA_PREP_INTERRUPT | DMA_CTRL_ACK); // Last
+ * ......
+ */
static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg(
struct dma_chan *chan, struct scatterlist *sgl,
unsigned int sg_len, enum dma_transfer_direction direction,
- unsigned long append)
+ unsigned long flags)
{
struct mxs_dma_chan *mxs_chan = to_mxs_dma_chan(chan);
struct mxs_dma_engine *mxs_dma = mxs_chan->mxs_dma;
@@ -360,6 +382,7 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg(
struct scatterlist *sg;
int i, j;
u32 *pio;
+ bool append = flags & DMA_PREP_INTERRUPT;
int idx = append ? mxs_chan->desc_count : 0;

if (mxs_chan->status == DMA_IN_PROGRESS && !append)
@@ -386,7 +409,6 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg(
ccw->bits |= CCW_CHAIN;
ccw->bits &= ~CCW_IRQ;
ccw->bits &= ~CCW_DEC_SEM;
- ccw->bits &= ~CCW_WAIT4END;
} else {
idx = 0;
}
@@ -401,7 +423,8 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg(
ccw->bits = 0;
ccw->bits |= CCW_IRQ;
ccw->bits |= CCW_DEC_SEM;
- ccw->bits |= CCW_WAIT4END;
+ if (flags & DMA_CTRL_ACK)
+ ccw->bits |= CCW_WAIT4END;
ccw->bits |= CCW_HALT_ON_TERM;
ccw->bits |= CCW_TERM_FLUSH;
ccw->bits |= BF_CCW(sg_len, PIO_NUM);
@@ -432,7 +455,8 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg(
ccw->bits &= ~CCW_CHAIN;
ccw->bits |= CCW_IRQ;
ccw->bits |= CCW_DEC_SEM;
- ccw->bits |= CCW_WAIT4END;
+ if (flags & DMA_CTRL_ACK)
+ ccw->bits |= CCW_WAIT4END;
}
}
}
diff --git a/drivers/mmc/host/mxs-mmc.c b/drivers/mmc/host/mxs-mmc.c
index 1e18970..120669b 100644
--- a/drivers/mmc/host/mxs-mmc.c
+++ b/drivers/mmc/host/mxs-mmc.c
@@ -305,7 +305,7 @@ static irqreturn_t mxs_mmc_irq_handler(int irq, void *dev_id)
}

static struct dma_async_tx_descriptor *mxs_mmc_prep_dma(
- struct mxs_mmc_host *host, unsigned int append)
+ struct mxs_mmc_host *host, unsigned long flags)
{
struct dma_async_tx_descriptor *desc;
struct mmc_data *data = host->data;
@@ -325,7 +325,7 @@ static struct dma_async_tx_descriptor *mxs_mmc_prep_dma(
}

desc = host->dmach->device->device_prep_slave_sg(host->dmach,
- sgl, sg_len, host->slave_dirn, append);
+ sgl, sg_len, host->slave_dirn, flags);
if (desc) {
desc->callback = mxs_mmc_dma_irq_callback;
desc->callback_param = host;
@@ -358,7 +358,7 @@ static void mxs_mmc_bc(struct mxs_mmc_host *host)
host->ssp_pio_words[2] = cmd1;
host->dma_dir = DMA_NONE;
host->slave_dirn = DMA_TRANS_NONE;
- desc = mxs_mmc_prep_dma(host, 0);
+ desc = mxs_mmc_prep_dma(host, DMA_CTRL_ACK);
if (!desc)
goto out;

@@ -398,7 +398,7 @@ static void mxs_mmc_ac(struct mxs_mmc_host *host)
host->ssp_pio_words[2] = cmd1;
host->dma_dir = DMA_NONE;
host->slave_dirn = DMA_TRANS_NONE;
- desc = mxs_mmc_prep_dma(host, 0);
+ desc = mxs_mmc_prep_dma(host, DMA_CTRL_ACK);
if (!desc)
goto out;

@@ -526,7 +526,7 @@ static void mxs_mmc_adtc(struct mxs_mmc_host *host)
host->data = data;
host->dma_dir = dma_data_dir;
host->slave_dirn = slave_dirn;
- desc = mxs_mmc_prep_dma(host, 1);
+ desc = mxs_mmc_prep_dma(host, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc)
goto out;

diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
index 7f68042..2029995 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
@@ -133,6 +133,9 @@ int gpmi_init(struct gpmi_nand_data *this)
if (ret)
goto err_out;

+ /* Read out the GPMI version */
+ this->gpmi_version = readl(r->gpmi_regs + HW_GPMI_VERSION);
+
/* Choose NAND mode. */
writel(BM_GPMI_CTRL1_GPMI_MODE, r->gpmi_regs + HW_GPMI_CTRL1_CLR);

@@ -839,7 +842,9 @@ int gpmi_send_command(struct gpmi_nand_data *this)
sg_init_one(sgl, this->cmd_buffer, this->command_length);
dma_map_sg(this->dev, sgl, 1, DMA_TO_DEVICE);
desc = channel->device->device_prep_slave_sg(channel,
- sgl, 1, DMA_MEM_TO_DEV, 1);
+ sgl, 1, DMA_MEM_TO_DEV,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+
if (!desc) {
pr_err("step 2 error\n");
return -1;
@@ -881,7 +886,8 @@ int gpmi_send_data(struct gpmi_nand_data *this)
/* [2] send DMA request */
prepare_data_dma(this, DMA_TO_DEVICE);
desc = channel->device->device_prep_slave_sg(channel, &this->data_sgl,
- 1, DMA_MEM_TO_DEV, 1);
+ 1, DMA_MEM_TO_DEV,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc) {
pr_err("step 2 error\n");
return -1;
@@ -917,7 +923,8 @@ int gpmi_read_data(struct gpmi_nand_data *this)
/* [2] : send DMA request */
prepare_data_dma(this, DMA_FROM_DEVICE);
desc = channel->device->device_prep_slave_sg(channel, &this->data_sgl,
- 1, DMA_DEV_TO_MEM, 1);
+ 1, DMA_DEV_TO_MEM,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc) {
pr_err("step 2 error\n");
return -1;
@@ -964,7 +971,8 @@ int gpmi_send_page(struct gpmi_nand_data *this,

desc = channel->device->device_prep_slave_sg(channel,
(struct scatterlist *)pio,
- ARRAY_SIZE(pio), DMA_TRANS_NONE, 0);
+ ARRAY_SIZE(pio), DMA_TRANS_NONE,
+ DMA_CTRL_ACK);
if (!desc) {
pr_err("step 2 error\n");
return -1;
@@ -984,6 +992,7 @@ int gpmi_read_page(struct gpmi_nand_data *this,
struct dma_async_tx_descriptor *desc;
struct dma_chan *channel = get_dma_chan(this);
int chip = this->current_chip;
+ unsigned long flags;
u32 pio[6];

/* [1] Wait for the chip to report ready. */
@@ -1026,9 +1035,14 @@ int gpmi_read_page(struct gpmi_nand_data *this,
pio[3] = geo->page_size;
pio[4] = payload;
pio[5] = auxiliary;
+
+ /* Check GPMI's version, set DMA_CTRL_ACK if needed. */
+ flags = DMA_PREP_INTERRUPT;
+ if (this->gpmi_version == GPMI_VERSION_0501)
+ flags |= DMA_CTRL_ACK;
desc = channel->device->device_prep_slave_sg(channel,
(struct scatterlist *)pio,
- ARRAY_SIZE(pio), DMA_TRANS_NONE, 1);
+ ARRAY_SIZE(pio), DMA_TRANS_NONE, flags);
if (!desc) {
pr_err("step 2 error\n");
return -1;
@@ -1045,9 +1059,11 @@ int gpmi_read_page(struct gpmi_nand_data *this,
| BF_GPMI_CTRL0_ADDRESS(address)
| BF_GPMI_CTRL0_XFER_COUNT(geo->page_size);
pio[1] = 0;
+ pio[2] = 0;
desc = channel->device->device_prep_slave_sg(channel,
(struct scatterlist *)pio, 2,
- DMA_TRANS_NONE, 1);
+ DMA_TRANS_NONE,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc) {
pr_err("step 3 error\n");
return -1;
diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
index 1c7fdbb..5c277e3 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
@@ -132,6 +132,10 @@ struct gpmi_nand_data {
/* Flash Hardware */
struct nand_timing timing;

+ /* GPMI hardware version */
+#define GPMI_VERSION_0501 (0x05010000)
+ u32 gpmi_version;
+
/* BCH */
struct bch_geometry bch_geometry;
struct completion bch_done;
diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-regs.h b/drivers/mtd/nand/gpmi-nand/gpmi-regs.h
index 8343124..f005b24 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-regs.h
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-regs.h
@@ -169,4 +169,6 @@
#define HW_GPMI_DEBUG 0x000000c0
#define MX23_BP_GPMI_DEBUG_READY0 28
#define MX23_BM_GPMI_DEBUG_READY0 (1 << MX23_BP_GPMI_DEBUG_READY0)
+
+#define HW_GPMI_VERSION 0x000000d0
#endif
--
1.7.3.2



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