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spi: cadence-qspi: add no-IRQ mode to indirect reads

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Support reads through polling, without any IRQ. The main reason is
performance; profiling shows that the first IRQ comes quickly on our
specific hardware. Once this IRQ arrives, we poll until all data is
retrieved. Avoid initial sleep to reduce IRQ count.

Hide this behavior behind a quirk flag.

This is confirmed through micro-benchmarks, but also end-to-end
performance tests. Mobileye EyeQ5, octal flash, reading 235M on a UBIFS
filesystem:
 - No optimizations, ~10.34s, ~22.7 MB/s, 199230 IRQs
 - CQSPI_SLOW_SRAM,  ~10.34s, ~22.7 MB/s,  70284 IRQs
 - CQSPI_RD_NO_IRQ,   ~9.37s, ~25.1 MB/s,    521 IRQs

Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Link: https://lore.kernel.org/r/20240423-cdns-qspi-mbly-v4-2-3d2a7b535ad0@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Théo Lebrun 2024-04-23 12:01:41 +02:00 committed by Mark Brown
parent 3bf64a2b66
commit 1f257b92e6
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
1 changed files with 9 additions and 4 deletions
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13
drivers/spi/spi-cadence-quadspi.c
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@ -42,6 +42,7 @@ static_assert(CQSPI_MAX_CHIPSELECT <= SPI_CS_CNT_MAX);
#define CQSPI_NO_SUPPORT_WR_COMPLETION BIT(3)
#define CQSPI_SLOW_SRAM BIT(4)
#define CQSPI_NEEDS_APB_AHB_HAZARD_WAR BIT(5)
#define CQSPI_RD_NO_IRQ BIT(6)
/* Capabilities */
#define CQSPI_SUPPORTS_OCTAL BIT(0)
@ -702,6 +703,7 @@ static int cqspi_indirect_read_execute(struct cqspi_flash_pdata *f_pdata,
const size_t n_rx)
{
struct cqspi_st *cqspi = f_pdata->cqspi;
bool use_irq = !(cqspi->ddata && cqspi->ddata->quirks & CQSPI_RD_NO_IRQ);
struct device *dev = &cqspi->pdev->dev;
void __iomem *reg_base = cqspi->iobase;
void __iomem *ahb_base = cqspi->ahb_base;
@ -725,17 +727,20 @@ static int cqspi_indirect_read_execute(struct cqspi_flash_pdata *f_pdata,
* all the read interrupts disabled for max performance.
*/
if (!cqspi->slow_sram)
if (use_irq && cqspi->slow_sram)
writel(CQSPI_REG_IRQ_WATERMARK, reg_base + CQSPI_REG_IRQMASK);
else if (use_irq)
writel(CQSPI_IRQ_MASK_RD, reg_base + CQSPI_REG_IRQMASK);
else
writel(CQSPI_REG_IRQ_WATERMARK, reg_base + CQSPI_REG_IRQMASK);
writel(0, reg_base + CQSPI_REG_IRQMASK);
reinit_completion(&cqspi->transfer_complete);
writel(CQSPI_REG_INDIRECTRD_START_MASK,
reg_base + CQSPI_REG_INDIRECTRD);
while (remaining > 0) {
if (!wait_for_completion_timeout(&cqspi->transfer_complete,
if (use_irq &&
!wait_for_completion_timeout(&cqspi->transfer_complete,
msecs_to_jiffies(CQSPI_READ_TIMEOUT_MS)))
ret = -ETIMEDOUT;
@ -777,7 +782,7 @@ static int cqspi_indirect_read_execute(struct cqspi_flash_pdata *f_pdata,
bytes_to_read = cqspi_get_rd_sram_level(cqspi);
}
if (remaining > 0) {
if (use_irq && remaining > 0) {
reinit_completion(&cqspi->transfer_complete);
if (cqspi->slow_sram)
writel(CQSPI_REG_IRQ_WATERMARK, reg_base + CQSPI_REG_IRQMASK);