On Thu, 2024-01-25 at 17:57 +0100, Rafael J. Wysocki wrote: > On Thu, Jan 25, 2024 at 4:31 PM Nuno Sá <noname.nuno@xxxxxxxxx> wrote: > > > > On Thu, 2024-01-25 at 09:14 +0100, Nuno Sá wrote: > > > > > > Hi Saravana, > > > > > > Thanks for your feedback, > > > > > > On Wed, 2024-01-24 at 19:21 -0800, Saravana Kannan wrote: > > > > On Tue, Jan 23, 2024 at 7:14 AM Nuno Sa via B4 Relay > > > > <devnull+nuno.sa.analog.com@xxxxxxxxxx> wrote: > > > > > > > > > > From: Nuno Sa <nuno.sa@xxxxxxxxxx> > > > > > > > > > > If a device_link is previously created (eg: via > > > > > fw_devlink_create_devlink()) before the supplier + consumer are both > > > > > present and bound to their respective drivers, there's no way to set > > > > > DL_FLAG_AUTOREMOVE_CONSUMER anymore while one can still set > > > > > DL_FLAG_AUTOREMOVE_SUPPLIER. Hence, rework the flags checks to allow > > > > > for DL_FLAG_AUTOREMOVE_CONSUMER in the same way > > > > > DL_FLAG_AUTOREMOVE_SUPPLIER is done. > > > > > > > > Curious, why do you want to set DL_FLAG_AUTOREMOVE_CONSUMER? > > > > Especially if fw_devlink already created the link? You are effectively > > > > trying to delete the link fw_devlink created if any of your devices > > > > unbind. > > > > > > > > > > Well, this is still useful in the modules case as the link will be relaxed > > > after > > > all devices are initialized and that will already clear AUTOPROBE_CONSUMER > > > AFAIU. But, more importantly, if I'm not missing anything, in [1], > > > fw_devlinks > > > will be dropped after the consumer + supplier are bound which means I > > > definitely > > > want to create a link between my consumer and supplier. > > > > > > > Ok, so to add a bit more on this, there are two cases: > > > > 1) Both sup and con are modules and after boot up, the link is relaxed and > > thus > > turned into a sync_state_only link. That means the link will be deleted > > anyways > > and AUTOPROBE_CONSUMER is already cleared by the time we try to change the > > link. > > > > 2) The built-in case where the link is kept as created by fw_devlink and > > this > > patch effectively clears AUTOPROBE_CONSUMER. > > > > Given the above, not sure what's the best option. I can think of 4: > > > > 1) Drop this patch and leave things as they are. DL_FLAG_AUTOREMOVE_CONSUMER > > is > > pretty much ignored in my call but it will turn the link in a MANAGED one > > and > > clear SYNC_STATE_ONLY. I could very well just pass 0 in the flags as > > DL_FLAG_AUTOREMOVE_CONSUMER is always ignored; > > > > 2) Rework this patch so we can still change an existing link to accept > > DL_FLAG_AUTOREMOVE_CONSUMER (in the modules case for example). > > > > However, instead of clearing AUTOPROBE_CONSUMER, I would add some checks so > > if > > flags have one of DL_FLAG_AUTOREMOVE_SUPPLIER or DL_FLAG_AUTOREMOVE_CONSUMER > > and > > AUTOPROBE_CONSUMER is already set, we ignore them. In fact, right now, I > > think > > one could pass DL_FLAG_AUTOREMOVE_SUPPLIER and link->flags ends ups with > > AUTOREMOVE_SUPPLIER | AUTOPROBE_CONSUMER which in theory is not allowed... > > No, because DL_FLAG_AUTOREMOVE_SUPPLIER is only added to the link > flags if DL_FLAG_AUTOREMOVE_CONSUMER is already set in there and the > former replaces the latter. > Oh yes, I missed that extra if() against the DL_FLAG_AUTOREMOVE_CONSUMER flag... > Now, DL_FLAG_AUTOREMOVE_CONSUMER cannot be set in the link flags if > AUTOPROBE_CONSUMER is set in there. > > > 3) Keep it as-is... This one is likely a NACK as I'm getting the feeling > > that > > clearing stuff that might have been created by fw_devlinks is probably a no- > > go. > > > > Let me know your thoughts... > > If the original creator of the link didn't indicate either > DL_FLAG_AUTOREMOVE_CONSUMER, or DL_FLAG_AUTOREMOVE_SUPPLIER, they are > expected to need the link to stay around until it is explicitly > deleted. > > Therefore adding any of these flags for an existing link where they > both are unset would be a mistake, because it would effectively cause > the link to live shorter than expected by the original creator and > that might lead to correctness issues. > > Thanks! Thanks Rafael, your last two paragraphs make it really clear what's the reasoning and why this patch is wrong. Jonathan, if nothing else comes that I need a re-spin, can you drop this patch when applying? I think we can keep the DL_FLAG_AUTOREMOVE_CONSUMER in the device_link_add() call as it will be ignored if fw_devlinks already created the link but might be important if the kernel command line fw_devlink is set to 'off'. Or maybe, as Saravan mentioned in his reply we can just pass DL_FLAG_MANAGED as having the link around is useful in case we re-probe so we don't need to call the consumer probe function (just to EPROBE_DEFER) without the supplier being already there... - Nuno Sá
