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net: dsa: microchip: Add shared regmap mutex

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The KSZ driver uses one regmap per register width (8/16/32), each with
it's own lock, but accessing the same set of registers. In theory, it
is possible to create a race condition between these regmaps, although
the underlying bus (SPI or I2C) locking should assure nothing bad will
really happen and the accesses would be correct.

To make the driver do the right thing, add one single shared mutex for
all the regmaps used by the driver instead. This assures that even if
some future hardware is on a bus which does not serialize the accesses
the same way SPI or I2C does, nothing bad will happen.

Note that the status_mutex was unused and only initied, hence it was
renamed and repurposed as the regmap mutex.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: David S. Miller <davem@davemloft.net>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: George McCollister <george.mccollister@gmail.com>
Cc: Tristram Ha <Tristram.Ha@microchip.com>
Cc: Woojung Huh <woojung.huh@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Marek Vasut
2019-10-16 15:33:24 +02:00
committed by David S. Miller
parent 7f238ca984
commit 013572a236
5 changed files with 28 additions and 9 deletions
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7
drivers/net/dsa/microchip/ksz8795_spi.c
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@@ -25,6 +25,7 @@ KSZ_REGMAP_TABLE(ksz8795, 16, SPI_ADDR_SHIFT,
static int ksz8795_spi_probe(struct spi_device *spi)
{
struct regmap_config rc;
struct ksz_device *dev;
int i, ret;
@@ -33,9 +34,9 @@ static int ksz8795_spi_probe(struct spi_device *spi)
return -ENOMEM;
for (i = 0; i < ARRAY_SIZE(ksz8795_regmap_config); i++) {
dev->regmap[i] = devm_regmap_init_spi(spi,
&ksz8795_regmap_config
[i]);
rc = ksz8795_regmap_config[i];
rc.lock_arg = &dev->regmap_mutex;
dev->regmap[i] = devm_regmap_init_spi(spi, &rc);
if (IS_ERR(dev->regmap[i])) {
ret = PTR_ERR(dev->regmap[i]);
dev_err(&spi->dev,