From: Bjorn Andersson <email@example.com> To: John Stultz <firstname.lastname@example.org> Cc: Rob Clark <email@example.com>, Dmitry Baryshkov <firstname.lastname@example.org>, Vinod Koul <email@example.com>, Srini Kandagatla <firstname.lastname@example.org>, Amit Pundir <email@example.com>, YongQin Liu <firstname.lastname@example.org>, linux-arm-msm <email@example.com> Subject: Re: Regression: arm64: dts: sdm845-db845c: make firmware filenames follow linux-firmware Date: Wed, 5 May 2021 16:02:40 -0500 [thread overview] Message-ID: <20210505210240.GH2484@yoga> (raw) In-Reply-To: <CALAqxLVxURmmJ227n8ozzsV96qqAxB+BdVV_kHbgFS7680=dbA@mail.gmail.com> On Wed 05 May 14:35 CDT 2021, John Stultz wrote: > On Wed, May 5, 2021 at 8:04 AM Rob Clark <firstname.lastname@example.org> wrote: > > On Tue, May 4, 2021 at 11:37 PM John Stultz <email@example.com> wrote: > > > Hey Dmitry, Bjorn, > > > I wanted to raise a regression I caught in the merge window on db845c. > > > > > > I was seeing troubles with audio and while there are a few other > > > pending fixes needed, they did not seem to work for me. So I spent > > > some time bisecting things down and found the problematic commit was > > > 7443ff06da45 ("arm64: dts: sdm845-db845c: make firmware filenames > > > follow linux-firmware"). > > > > > > It seems for systems using the old firmware filenames, this will break > > > dependent devices on adsp_pas and cdsp_pas nodes. > > > > > > Now, obviously updating the firmware files in userland should resolve > > > this, but it adds the complexity that we can't just replace the > > > firmware files because older LTS kernels will look for the old names, > > > while newer kernels will look for the new names. We can add both files > > > to the system images, but then there is some confusion on which > > > version of the firmware files are being used where. > > > > > > So yes, we should align with linux-firmware file names, but I think > > > more care is needed for this sort of thing as it has the potential to > > > break folks, and this isn't the first time around we've had similar > > > firmware name changes break us. > > > > > > So I'm working on fixing this by including both filenames in userland, > > > so we probably don't need a revert here, but *please* maybe take more > > > care on this sort of change. > > > > > > > It is rather more difficult than you think, because if you try the > > wrong path you could end up waiting with a timeout.. we have > > shenanigans to work around that for gpu fw in drm/msm to avoid this > > sort of regression with people using downstream firmware trees. I'd > > like to rip that out at some point, but I suppose doing so would be > > problematic for folks doing upstream kernel on android devices. > > > > Maybe there is some way to add support to simultaneously > > request_firmware for two different paths at the same time.. not sure > > how that would work from the PoV of the usermode helper path. > > > > It really is a lot of pain to deal with downstream firmware layout.. > > Yeah, but on other platforms, the kernel has to meet and deal with the > hardware, firmware and userland as it exists in the world. The whole problem is that the kernel _didn't_ work with the firmware that was published to the world, we used the wrong firmware name and because you and apparently the LT releases doesn't follow linux-firmware this was not noticed until now. > It would be quite a thing if an upstream kernel change required a new > BIOS update which then made the system incompatible with the most > recent LTS. > Certainly so, but even if we didn't have to deal with OEM-signed, per-board firmware files we'd have to hard code the file names in the drivers - and would have run into this problem anyways. > And yes, I'm very sympathetic that it's a pain (In the timekeeping > code, there's a ton of messy duplicative code required to keep > timespec alongside of ktime_t representations of time so we can be > fast no matter which interface is used). :) > > And again, I can work around this one. It's just that this isn't the > first time, so I want to nudge folks to have a broader view and > consider these issues a little more when making changes (not just in > the kernel, but in why the names in linux-firmware are different then > what's on devices in the field, etc). > Right, you certainly have suffered from this in the past, because we didn't have a strategy for handling more than a single Qualcomm device with any given instance of /lib/firmware. Now we have a plan, and I believe db845c was the first board to implement this plan and I got it wrong. Going forward I hope to avoid making this mistake again. Regards, Bjorn
next prev parent reply other threads:[~2021-05-05 21:02 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-05 6:20 John Stultz 2021-05-05 15:08 ` Rob Clark 2021-05-05 19:35 ` John Stultz 2021-05-05 20:05 ` Rob Clark 2021-05-05 20:07 ` Dmitry Baryshkov 2021-05-05 21:14 ` John Stultz 2021-05-05 21:02 ` Bjorn Andersson [this message] 2021-05-05 18:43 ` Dmitry Baryshkov 2021-05-05 19:06 ` Bjorn Andersson
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