4.19-stable review patch. If anyone has any objections, please let me know.
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From: Florian Fainelli florian.fainelli@broadcom.com
commit f16dd10ba342c429b1e36ada545fb36d4d1f0e63 upstream.
The write to RP2_GLOBAL_CMD followed by an immediate read of RP2_GLOBAL_CMD in rp2_reset_asic() is intented to flush out the write, however by then the device is already in reset and cannot respond to a memory cycle access.
On platforms such as the Raspberry Pi 4 and others using the pcie-brcmstb.c driver, any memory access to a device that cannot respond is met with a fatal system error, rather than being substituted with all 1s as is usually the case on PC platforms.
Swapping the delay and the read ensures that the device has finished resetting before we attempt to read from it.
Fixes: 7d9f49afa451 ("serial: rp2: New driver for Comtrol RocketPort 2 cards") Cc: stable stable@kernel.org Suggested-by: Jim Quinlan james.quinlan@broadcom.com Signed-off-by: Florian Fainelli florian.fainelli@broadcom.com Link: https://lore.kernel.org/r/20240906225435.707837-1-florian.fainelli@broadcom.... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/serial/rp2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/tty/serial/rp2.c +++ b/drivers/tty/serial/rp2.c @@ -600,8 +600,8 @@ static void rp2_reset_asic(struct rp2_ca u32 clk_cfg;
writew(1, base + RP2_GLOBAL_CMD); - readw(base + RP2_GLOBAL_CMD); msleep(100); + readw(base + RP2_GLOBAL_CMD); writel(0, base + RP2_CLK_PRESCALER);
/* TDM clock configuration */