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Subject[PATCH v2 2/3] fpga: microchip-spi: rewrite status polling in a time measurable way
Date
Original busy loop with retries count in mpf_poll_status() is not too
reliable, as it takes different times on different systems. Replace it
with read_poll_timeout() macro.

Fixes: 5f8d4a900830 ("fpga: microchip-spi: add Microchip MPF FPGA manager")
Signed-off-by: Ivan Bornyakov <i.bornyakov@metrotek.ru>
---
drivers/fpga/microchip-spi.c | 25 +++++++++++--------------
1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/drivers/fpga/microchip-spi.c b/drivers/fpga/microchip-spi.c
index e72fedd93a27..f3ddfab87499 100644
--- a/drivers/fpga/microchip-spi.c
+++ b/drivers/fpga/microchip-spi.c
@@ -6,6 +6,7 @@
#include <asm/unaligned.h>
#include <linux/delay.h>
#include <linux/fpga/fpga-mgr.h>
+#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/spi/spi.h>
@@ -33,7 +34,7 @@

#define MPF_BITS_PER_COMPONENT_SIZE 22

-#define MPF_STATUS_POLL_RETRIES 10000
+#define MPF_STATUS_POLL_TIMEOUT (2 * USEC_PER_SEC)
#define MPF_STATUS_BUSY BIT(0)
#define MPF_STATUS_READY BIT(1)
#define MPF_STATUS_SPI_VIOLATION BIT(2)
@@ -197,21 +198,17 @@ static int mpf_ops_parse_header(struct fpga_manager *mgr,
/* Poll HW status until busy bit is cleared and mask bits are set. */
static int mpf_poll_status(struct mpf_priv *priv, u8 mask)
{
- int status, retries = MPF_STATUS_POLL_RETRIES;
+ int ret, status;

- while (retries--) {
- status = mpf_read_status(priv);
- if (status < 0)
- return status;
-
- if (status & MPF_STATUS_BUSY)
- continue;
-
- if (!mask || (status & mask))
- return status;
- }
+ ret = read_poll_timeout(mpf_read_status, status,
+ (status < 0) ||
+ (!(status & MPF_STATUS_BUSY) &&
+ (!mask || (status & mask))),
+ 0, MPF_STATUS_POLL_TIMEOUT, false, priv);
+ if (ret < 0)
+ return ret;

- return -EBUSY;
+ return status;
}

static int mpf_spi_write(struct mpf_priv *priv, const void *buf, size_t buf_size)
--
2.38.2

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