Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-22 20:22:09 +00:00
Code Issues Packages Projects Releases Wiki Activity

fpga: microchip-spi: rewrite status polling in a time measurable way

Browse Source 
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.

While at it, fix polling stop condition to met function's original
intention declared in the comment. The issue with original polling stop
condition is that it stops if any of mask bits is set, while intention
was to stop if all mask bits is set. This was not noticible because only
MPF_STATUS_READY is passed as mask argument and it is BIT(1).

Fixes: 5f8d4a9008 ("fpga: microchip-spi: add Microchip MPF FPGA manager")
Signed-off-by: Ivan Bornyakov <i.bornyakov@metrotek.ru>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Xu Yilun <yilun.xu@intel.com>
Link: https://lore.kernel.org/r/20221230092922.18822-3-i.bornyakov@metrotek.ru
Signed-off-by: Xu Yilun <yilun.xu@intel.com>
This commit is contained in:
Ivan Bornyakov 2022-12-30 12:29:21 +03:00 committed by Xu Yilun
parent 1da53d23a4
commit 88e705697e
No known key found for this signature in database
GPG Key ID: FCB70381A4A08CDA
1 changed files with 17 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
drivers/fpga/microchip-spi.c
View File

@ -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)
@ -194,24 +195,25 @@ static int mpf_ops_parse_header(struct fpga_manager *mgr,
return 0;
}
/* 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;
/*
* Busy poll HW status. Polling stops if any of the following
* conditions are met:
* - timeout is reached
* - mpf_read_status() returns an error
* - busy bit is cleared AND mask bits are set
*/
ret = read_poll_timeout(mpf_read_status, status,
(status < 0) ||
((status & (MPF_STATUS_BUSY | mask)) == mask),
0, MPF_STATUS_POLL_TIMEOUT, false, priv);
if (ret < 0)
return ret;
if (status & MPF_STATUS_BUSY)
continue;
if (!mask || (status & mask))
return status;
}
return -EBUSY;
return status;
}
static int mpf_spi_write(struct mpf_priv *priv, const void *buf, size_t buf_size)