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spi: spi-fsl-dspi: Use poll mode in case the platform IRQ is missing 

On platforms like LS1021A which use TCFQ mode, an interrupt needs to be
processed after each byte is TXed/RXed. I tried to make the DSPI
implementation on this SoC operate in other, more efficient modes (EOQ,
DMA) but it looks like it simply isn't possible.

Therefore allow the driver to operate in poll mode, to ease a bit of
this absurd amount of IRQ load generated in TCFQ mode. Doing so reduces
both the net time it takes to transmit a SPI message, as well as the
inter-frame jitter that occurs while doing so.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20190822211514.19288-5-olteanv@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
alistair/sunxi64-5.4-dsi
Vladimir Oltean 2019-08-23 00:15:13 +03:00 committed by Mark Brown
parent 1eaeba7073
commit c55be30591
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
1 changed files with 64 additions and 23 deletions
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87
drivers/spi/spi-fsl-dspi.c
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@ -647,19 +647,12 @@ static void dspi_eoq_read(struct fsl_dspi *dspi)
dspi_push_rx(dspi, fifo_read(dspi));
}
static irqreturn_t dspi_interrupt(int irq, void *dev_id)
static int dspi_rxtx(struct fsl_dspi *dspi)
{
struct fsl_dspi *dspi = (struct fsl_dspi *)dev_id;
struct spi_message *msg = dspi->cur_msg;
enum dspi_trans_mode trans_mode;
u32 spi_sr, spi_tcr;
u16 spi_tcnt;
regmap_read(dspi->regmap, SPI_SR, &spi_sr);
regmap_write(dspi->regmap, SPI_SR, spi_sr);
if (!(spi_sr & (SPI_SR_EOQF | SPI_SR_TCFQF)))
return IRQ_NONE;
u32 spi_tcr;
/* Get transfer counter (in number of SPI transfers). It was
* reset to 0 when transfer(s) were started.
@ -675,17 +668,55 @@ static irqreturn_t dspi_interrupt(int irq, void *dev_id)
else if (trans_mode == DSPI_TCFQ_MODE)
dspi_tcfq_read(dspi);
if (!dspi->len) {
dspi->waitflags = 1;
wake_up_interruptible(&dspi->waitq);
return IRQ_HANDLED;
}
if (!dspi->len)
/* Success! */
return 0;
if (trans_mode == DSPI_EOQ_MODE)
dspi_eoq_write(dspi);
else if (trans_mode == DSPI_TCFQ_MODE)
dspi_tcfq_write(dspi);
return -EINPROGRESS;
}
static int dspi_poll(struct fsl_dspi *dspi)
{
int tries = 1000;
u32 spi_sr;
do {
regmap_read(dspi->regmap, SPI_SR, &spi_sr);
regmap_write(dspi->regmap, SPI_SR, spi_sr);
if (spi_sr & (SPI_SR_EOQF | SPI_SR_TCFQF))
break;
} while (--tries);
if (!tries)
return -ETIMEDOUT;
return dspi_rxtx(dspi);
}
static irqreturn_t dspi_interrupt(int irq, void *dev_id)
{
struct fsl_dspi *dspi = (struct fsl_dspi *)dev_id;
u32 spi_sr;
regmap_read(dspi->regmap, SPI_SR, &spi_sr);
regmap_write(dspi->regmap, SPI_SR, spi_sr);
if (!(spi_sr & (SPI_SR_EOQF | SPI_SR_TCFQF)))
return IRQ_NONE;
dspi_rxtx(dspi);
if (!dspi->len) {
dspi->waitflags = 1;
wake_up_interruptible(&dspi->waitq);
}
return IRQ_HANDLED;
}
@ -773,13 +804,18 @@ static int dspi_transfer_one_message(struct spi_controller *ctlr,
goto out;
}
if (trans_mode != DSPI_DMA_MODE) {
if (wait_event_interruptible(dspi->waitq,
dspi->waitflags))
dev_err(&dspi->pdev->dev,
"wait transfer complete fail!\n");
if (!dspi->irq) {
do {
status = dspi_poll(dspi);
} while (status == -EINPROGRESS);
} else if (trans_mode != DSPI_DMA_MODE) {
status = wait_event_interruptible(dspi->waitq,
dspi->waitflags);
dspi->waitflags = 0;
}
if (status)
dev_err(&dspi->pdev->dev,
"Waiting for transfer to complete failed!\n");
if (transfer->delay_usecs)
udelay(transfer->delay_usecs);
@ -1079,10 +1115,13 @@ static int dspi_probe(struct platform_device *pdev)
goto out_ctlr_put;
dspi_init(dspi);
dspi->irq = platform_get_irq(pdev, 0);
if (dspi->irq < 0) {
ret = dspi->irq;
goto out_clk_put;
if (dspi->irq <= 0) {
dev_info(&pdev->dev,
"can't get platform irq, using poll mode\n");
dspi->irq = 0;
goto poll_mode;
}
ret = devm_request_irq(&pdev->dev, dspi->irq, dspi_interrupt,
@ -1092,6 +1131,9 @@ static int dspi_probe(struct platform_device *pdev)
goto out_clk_put;
}
init_waitqueue_head(&dspi->waitq);
poll_mode:
if (dspi->devtype_data->trans_mode == DSPI_DMA_MODE) {
ret = dspi_request_dma(dspi, res->start);
if (ret < 0) {
@ -1103,7 +1145,6 @@ static int dspi_probe(struct platform_device *pdev)
ctlr->max_speed_hz =
clk_get_rate(dspi->clk) / dspi->devtype_data->max_clock_factor;
init_waitqueue_head(&dspi->waitq);
platform_set_drvdata(pdev, ctlr);
ret = spi_register_controller(ctlr);