From af4a062e5e67402083e1748f1661972632816a70 Mon Sep 17 00:00:00 2001 From: Wolfgang Müller Date: Tue, 5 Nov 2024 23:40:10 +0100 Subject: content: Add post: "Adding Zero RPM controls to the RX 7000 series" --- content/27/index.md | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 content/27/index.md (limited to 'content') diff --git a/content/27/index.md b/content/27/index.md new file mode 100644 index 0000000..f1f7ac8 --- /dev/null +++ b/content/27/index.md @@ -0,0 +1,65 @@ ++++ +date = 2024-11-05T23:39:57+01:00 +title = "Adding Zero RPM controls to the RX 7000 series" + +[taxonomies] +tags = ["contrib"] + +[extra] +related = [] ++++ + +Last year I upgraded to an AMD RX 7900XTX, mainly to play Alan Wake II. Just +like my previous card the XTX has a "Zero RPM" feature: it turns off its fans +fully if the junction temperature, the hottest part of the GPU, is below a +certain threshold. With the fans off, the GPU relies on its massive heatsink for +passive cooling. Even in a very well-ventilated case, however, this will mean +that the area around the GPU will heat up considerably. For me the fans turn off +at around 55°C; the component closest to the GPU, an NVMe M.2 SSD, will usually +slowly heat up to around 48°C whilst idling. + +Even under load the SSD never exceeds any temperature threshold, so +realistically it should be fine, but I'm simply not happy with the amount of +thermal energy sitting around in there if it could be expelled easily by turning +on the fans. Worse still, the logic for toggling the fans is not very well +thought-out, and in the worst case the fans are on for one minute only to be off +for the next one, ad nauseam. + +With my previous GPU turning off the "Zero RPM" was pretty simple. Using the +[upp(1)](https://github.com/sibradzic/upp) tool you could toggle the feature in +the GPU's so-called PowerPlay tables. It's a simple job, then, to write a +systemd service to turn off "Zero RPM" on system boot. + +Sadly this is no longer possible on 7000 series cards as there is no more direct +access to the PowerPlay tables. Instead a new framework using +[sysfs](https://www.kernel.org/doc/html/latest/filesystems/sysfs.html) for +managing PowerPlay features was introduced. [Fan +curve](https://gitlab.freedesktop.org/drm/amd/-/issues/2402) controls were added +after a while (and a lot of moaning by users), but there was no such knob for +the "Zero RPM" feature. A couple of months ago a [feature +request](https://gitlab.freedesktop.org/drm/amd/-/issues/3489) was opened for +it, but nothing much happened on AMD's side. + +Initially hopeful for a reasonably quick resolution, I was getting more and more +annoyed after a while by the lack of this seemingly simple toggle, so I finally +caved and proceeded to have a look at it myself. The hardest part was getting +started with reading +[amdgpu](https://gitlab.freedesktop.org/agd5f/linux/-/tree/amd-staging-drm-next/drivers/gpu/drm/amd?ref_type=heads) +code. The code base is absolutely massive and I had no real idea where to start. +Since fan curve controls already existed I thought it best to find the commit +that introduced them. After a quick search I found [the relevant +commit](https://gitlab.freedesktop.org/agd5f/linux/-/commit/eedd5a343d22) and +had a better understanding of which parts of the code to change. + +So, after a while of tweaking and twiddling I had a working prototype and I +could finally have my GPU run its fans at all times. I knew a lot of people were +also waiting for this feature, so I [sent a +patch](https://lists.freedesktop.org/archives/amd-gfx/2024-October/115857.html) +upstream. After some short feedback and [the addition of another +feature](https://lists.freedesktop.org/archives/amd-gfx/2024-October/116274.html) +the series was accepted, and is going to be part of the kernel sometime soon. + +With the fans now running at all times I can happily report that ambient +temperatures have dropped by more than 10°C and the SSD usually does not exceed +40°C when idling. Even better I do feel quite proud to have finally contributed +code to the kernel. -- cgit v1.2.3-2-gb3c3