On 09-09-20, 12:00, Pierre-Louis Bossart wrote: > On 9/9/20 10:54 AM, Srinivas Kandagatla wrote: > > On 09/09/2020 15:39, Pierre-Louis Bossart wrote: > > > > > > > > > Currently slave devices are only added either from device tree or acpi > > > > > > entries. However lets say, there is wrong or no entry of > > > > > > a slave device > > > > > > in DT that is enumerated, then there is no way for user to know all > > > > > > the enumerated devices on the bus. > > > > > > > > > > Sorry Srinivas, I don't understand your point. > > > > > > > > > > The sysfs entries will include all devices that are > > > > > described in platform firmware (be it DT or ACPI). > > > > > > > > yes that is true, but it will not include all the enumerated > > > > devices on the bus! > > > > > > > > In my case on a new board I was trying to figure out what > > > > devices are on the bus even before even adding any device tree > > > > entries! > > > > > > We've seen this before but dynamic debug provides all the > > > information you need. see e.g. the logs from > > > https://sof-ci.01.org/linuxpr/PR2425/build4447/devicetest/ > > > > > > jf-cml-rvp-sdw-1 kernel: [ 289.751974] soundwire sdw-master-0: > > > Slave attached, programming device number > > > jf-cml-rvp-sdw-1 kernel: [ 289.752121] soundwire sdw-master-0: SDW > > > Slave Addr: 10025d070000 <<< HERE > > > > Yes, I have noticed this too! This will be printed for every call to > > sdw_extract_slave_id()! > > > > ... > > > > > > Now I get your point but > > > a) you already have a dynamic debug trace to list all devices > > > b) adding 'undeclared' devices would make things quite murky and is > > > only half of the solution. We already struggle because we already > > > have 'ghost' devices in sysfs that are not physically present, and > > > no way to differentiate between the two. If we did add those > > > entries, then we'd need two new sysfs attributes such as > > > 'declared' and 'enumerated'. > > > > I totally agree with you on dealing with the undeclared devices, which > > is unnecessary mess! > > It's not necessarily that bad. > - if the intent is to have a single platform firmware that can deal with > different boards, it's a good thing. > - but if it's just sloppy platform firmware that just does copy-paste from > platform to platform then indeed it becomes a mess. > > > May be we could make the enumerated devices discovery bit more verbose! > > Maybe adding a device number sysfs entry would help, e.g. reporting > NotAttched or a value in [0,11] would tell you if the device is actually > present. Agreed, I cooked this patch to report verbose device status, let me know if you are okay with this. I think this would be useful regardless of current discussion. On Db845c I see: root@linaro-alip:/sys/bus/soundwire/devices# cat sdw:0:217:2010:0:1/status Attached root@linaro-alip:/sys/bus/soundwire/devices# cat sdw:0:217:2010:0:2/status Attached diff --git a/drivers/soundwire/sysfs_slave.c b/drivers/soundwire/sysfs_slave.c index f510071b0add..3b2765f10024 100644 --- a/drivers/soundwire/sysfs_slave.c +++ b/drivers/soundwire/sysfs_slave.c @@ -97,8 +97,27 @@ static ssize_t modalias_show(struct device *dev, } static DEVICE_ATTR_RO(modalias); +#define SDW_SLAVE_MAX (SDW_SLAVE_RESERVED + 1) + +static const char *const slave_status[SDW_SLAVE_MAX] = { + [SDW_SLAVE_UNATTACHED] = "UNATTACHED", + [SDW_SLAVE_ATTACHED] = "Attached", + [SDW_SLAVE_ALERT] = "Alert", + [SDW_SLAVE_RESERVED] = "Reserved", +}; + +static ssize_t status_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct sdw_slave *slave = dev_to_sdw_dev(dev); + + return sprintf(buf, "%s\n", slave_status[slave->status]); +} +static DEVICE_ATTR_RO(status); + static struct attribute *slave_attrs[] = { &dev_attr_modalias.attr, + &dev_attr_status.attr, NULL, }; ATTRIBUTE_GROUPS(slave); -- ~Vinod
