Hi, On Wed 27 Jul 22, 09:06, Saravana Kannan wrote: > On Wed, Jul 27, 2022 at 5:06 AM Maxime Ripard <maxime@xxxxxxxxxx> wrote: > > > > Hi, > > > > On Mon, Mar 07, 2022 at 07:34:22PM -0800, Saravana Kannan wrote: > > > On Mon, Mar 7, 2022 at 3:21 PM Rob Herring <robh@xxxxxxxxxx> wrote: > > > > > > > > +Saravana > > > > > > > > On Wed, Mar 02, 2022 at 10:10:53PM +0100, Paul Kocialkowski wrote: > > > > > In order to set their correct DMA address offset, some devices rely on > > > > > the device-tree interconnects property which identifies an > > > > > interconnect node that provides a dma-ranges property that can be used > > > > > to set said offset. > > > > > > > > > > Since that logic is all handled by the generic openfirmware and driver > > > > > code, the device-tree description could be enough to properly set > > > > > the offset. > > > > > > > > > > However the interconnects property is currently not marked as > > > > > optional, which implies that a driver for the corresponding node > > > > > must be loaded as a requirement. When no such driver exists, this > > > > > results in an endless EPROBE_DEFER which gets propagated to the > > > > > calling driver. This ends up in the driver never loading. > > > > > > > > > > Marking the interconnects property as optional makes it possible > > > > > to load the driver in that situation, since the EPROBE_DEFER return > > > > > code will no longer be propagated to the driver. > > > > > > > > > > There might however be undesirable consequences with this change, > > > > > which I do not fully grasp at this point. > > > > > > Temporary NACK till I get a bit more time to take a closer look. I > > > really don't like the idea of making interconnects optional. IOMMUs > > > and DMAs were exceptions. Also, we kinda discuss similar issues in > > > LPC. We had some consensus on how to handle these and I noted them all > > > down with a lot of details -- let me go take a look at those notes > > > again and see if I can send a more generic patch. > > > > > > Paul, > > > > > > Can you point to the DTS (not DTSI) file that corresponds to this? > > > Also, if it's a builtin kernel, I'd recommend setting > > > deferred_probe_timeout=1 and that should take care of it too. > > > > For the record, I also encountered this today on next-20220726 with this > > device: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/sun5i.dtsi#n775 > > > > The driver won't probe without fw_devlink=off > > Really? I basically ended up doing what I mentioned in my original > reply. next-20220726 should have my changes that'll make sure > fw_devlink doesn't block any probe (it'll still try to create as many > device links as possible) after 10s (default deferred probe timeout). > Can you try to find more info on why it's not probing? > <debugfs>/devices_deferred should give more details. By the way last time I checked the initial issue that I reported appeared to be fixed by the patch (Extend deferred probe timeout on driver registration). Cheers, Paul -- Paul Kocialkowski, Bootlin Embedded Linux and kernel engineering https://bootlin.com
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