From: Richard Fitzgerald Date: Wed, 14 Sep 2022 16:02:48 +0000 (+0100) Subject: soundwire: bus: Don't exit early if no device IDs were programmed X-Git-Tag: v6.1-rc5~266^2~18 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=72124f07f0fab446caeea1f545d8c58b7549a899;p=platform%2Fkernel%2Flinux-starfive.git soundwire: bus: Don't exit early if no device IDs were programmed 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 Reviewed-by: Pierre-Louis Bossart Link: https://lore.kernel.org/r/20220914160248.1047627-6-rf@opensource.cirrus.com Signed-off-by: Vinod Koul --- diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c index 6e569a8..8eded1a 100644 --- a/drivers/soundwire/bus.c +++ b/drivers/soundwire/bus.c @@ -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 */