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AJvYcCXh4fBcDqtXrajz6IBk6m02wtuNQaCVqc1DRq6PPrGaeLeU9iIK/WxCSw1Vaix0Vhy0s5C+/a1zNaUrxQaMC29iEUZqDTuPs8H8u2k= X-Gm-Message-State: AOJu0Ywf74cutc/s+IC1HbVsdKsofQQpQPAaC5MGUThgidAnEC1dOZrW UM4yngYGMIzkjmXQmaWW+dkkDuyBSqgg899BhbRuMxLfQwKqjzsWQT+rJCBlRFc= X-Google-Smtp-Source: AGHT+IEBBx5LsAEMyoM6oe7rtQrWY0rnpjUL/ghKQBCG5QRwkixQ4Ro9RCrukrZIHEiRAWSLTz45yw== X-Received: by 2002:a5d:6347:0:b0:35f:10ac:ea50 with SMTP id ffacd0b85a97d-36b5cefc0afmr5637864f8f.37.1722268626835; Mon, 29 Jul 2024 08:57:06 -0700 (PDT) Received: from localhost ([2a01:e0a:3c5:5fb1:abd3:cdc8:2363:54ef]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-36b3687003dsm12532306f8f.115.2024.07.29.08.57.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Jul 2024 08:57:06 -0700 (PDT) From: Jerome Brunet To: Mark Brown , linux-rt-users@vger.kernel.org Cc: Arseniy Krasnov , Liam Girdwood , Jaroslav Kysela , Takashi Iwai , Neil Armstrong , Kevin Hilman , Martin Blumenstingl , alsa-devel@alsa-project.org, linux-sound@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org, kernel@sberdevices.ru, oxffffaa@gmail.com Subject: Re: [PATCH v1] ASoC: meson: axg-fifo: set option to use raw spinlock In-Reply-To: <7dfdade5-3a57-4883-bfac-067c50ec0ffb@sirena.org.uk> (Mark Brown's message of "Mon, 29 Jul 2024 16:28:56 +0100") References: <20240729131652.3012327-1-avkrasnov@salutedevices.com> <1ja5i0wags.fsf@starbuckisacylon.baylibre.com> <2b16b95e-196e-4d8a-98c3-3be568cdd18a@sirena.org.uk> <1j5xsow839.fsf@starbuckisacylon.baylibre.com> <7dfdade5-3a57-4883-bfac-067c50ec0ffb@sirena.org.uk> Date: Mon, 29 Jul 2024 17:57:05 +0200 Message-ID: <1j1q3cw5ri.fsf@starbuckisacylon.baylibre.com> Precedence: bulk X-Mailing-List: linux-sound@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Mon 29 Jul 2024 at 16:28, Mark Brown wrote: > On Mon, Jul 29, 2024 at 05:06:50PM +0200, Jerome Brunet wrote: >> On Mon 29 Jul 2024 at 15:44, Mark Brown wrote: > >> > I don't recall this coming up much TBH. It may be that people just set >> > raw spinlocks when they need it, or that there's not many people using >> > relevant devices with RT kernels. > >> I have not been playing much with RT TBH, but AFAIK, with RT irq >> handlers are threaded unless IRQF_NO_THREAD is set. In this case, >> something preemptible in the handler should not be a problem. > >> The axg-fifo drivers do not have IRQF_NO_THREAD so something is a bit >> unclear here. > > Yeah, it's definitely likely to happen all the time for people using RT > with relevant devices. I'm not sure I have a good sense of if it's > likely to be a nasty surprise to switch raw spinlocks on by default when > it's currently controllable, I'd expect it'll generally be fine but it's > possibly a bit rude to any users that don't use interrupts... Indeed it is bit radical. My concern with this patch is that, IIUC, the handler should be threaded under RT and there should be no problem with the spinlock API. Adding the RT folks to try to get a better understanding, they should have been CCed anyway. -- Jerome