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soundwire: bus: Don't exit early if no device IDs were programmed

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Only exit sdw_handle_slave_status() right after calling
sdw_program_device_num() if it actually programmed an ID into at
least one device.

sdw_handle_slave_status() should protect itself against phantom
device #0 ATTACHED indications. In that case there is no actual
device still on #0. The early exit relies on there being a status
change to ATTACHED on the reprogrammed device to trigger another
call to sdw_handle_slave_status() which will then handle the status
of all peripherals. If no device was actually programmed with an
ID there won't be a new ATTACHED indication. This can lead to the
status of other peripherals not being handled.

The status passed to sdw_handle_slave_status() is obviously always
from a point of time in the past, and may indicate accumulated
unhandled events (depending how the bus manager operates). It's
possible that a device ID is reprogrammed but the last PING status
captured state just before that, when it was still reporting on
ID #0. Then sdw_handle_slave_status() is called with this PING info,
just before a new PING status is available showing it now on its new
ID. So sdw_handle_slave_status() will receive a phantom report of a
device on #0, but it will not find one.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20220914160248.1047627-6-rf@opensource.cirrus.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Richard Fitzgerald 2022-09-14 17:02:48 +01:00 committed by Vinod Koul
parent 0c5e99c415
commit 72124f07f0
1 changed files with 21 additions and 8 deletions
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29
drivers/soundwire/bus.c
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@ -729,7 +729,7 @@ void sdw_extract_slave_id(struct sdw_bus *bus,
}
EXPORT_SYMBOL(sdw_extract_slave_id);
static int sdw_program_device_num(struct sdw_bus *bus)
static int sdw_program_device_num(struct sdw_bus *bus, bool *programmed)
{
u8 buf[SDW_NUM_DEV_ID_REGISTERS] = {0};
struct sdw_slave *slave, *_s;
@ -739,6 +739,8 @@ static int sdw_program_device_num(struct sdw_bus *bus)
int count = 0, ret;
u64 addr;
*programmed = false;
/* No Slave, so use raw xfer api */
ret = sdw_fill_msg(&msg, NULL, SDW_SCP_DEVID_0,
SDW_NUM_DEV_ID_REGISTERS, 0, SDW_MSG_FLAG_READ, buf);
@ -797,6 +799,8 @@ static int sdw_program_device_num(struct sdw_bus *bus)
return ret;
}
*programmed = true;
break;
}
}
@ -1756,7 +1760,7 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
{
enum sdw_slave_status prev_status;
struct sdw_slave *slave;
bool attached_initializing;
bool attached_initializing, id_programmed;
int i, ret = 0;
/* first check if any Slaves fell off the bus */
@ -1787,14 +1791,23 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
if (status[0] == SDW_SLAVE_ATTACHED) {
dev_dbg(bus->dev, "Slave attached, programming device number\n");
ret = sdw_program_device_num(bus);
if (ret < 0)
dev_err(bus->dev, "Slave attach failed: %d\n", ret);
/*
* programming a device number will have side effects,
* so we deal with other devices at a later time
* Programming a device number will have side effects,
* so we deal with other devices at a later time.
* This relies on those devices reporting ATTACHED, which will
* trigger another call to this function. This will only
* happen if at least one device ID was programmed.
* Error returns from sdw_program_device_num() are currently
* ignored because there's no useful recovery that can be done.
* Returning the error here could result in the current status
* of other devices not being handled, because if no device IDs
* were programmed there's nothing to guarantee a status change
* to trigger another call to this function.
*/
return ret;
sdw_program_device_num(bus, &id_programmed);
if (id_programmed)
return 0;
}
/* Continue to check other slave statuses */