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Fri, 21 Jun 2024 08:48:32 +0100 Date: Fri, 21 Jun 2024 08:48:32 +0100 Message-ID: <8634p6ka7j.wl-maz@kernel.org> From: Marc Zyngier To: "Liao, Chang" Cc: Mark Rutland , , , , , , Subject: Re: [PATCH v2 5/5] arm64: irqchip/gic-v3: Select priorities at boot time In-Reply-To: <39b2bce8-3bc1-b1d9-3e4a-8132a92059c6@huawei.com> References: <20240617111841.2529370-1-mark.rutland@arm.com> <20240617111841.2529370-6-mark.rutland@arm.com> <39b2bce8-3bc1-b1d9-3e4a-8132a92059c6@huawei.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/29.2 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: liaochang1@huawei.com, mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org, alexandru.elisei@arm.com, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, will@kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240621_004836_412402_43AA13E9 X-CRM114-Status: GOOD ( 16.68 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 21 Jun 2024 07:23:54 +0100, "Liao, Chang" wrote: >=20 >=20 >=20 > =E5=9C=A8 2024/6/17 19:18, Mark Rutland =E5=86=99=E9=81=93: > > cpus_have_group0 =3D gic_has_group0(); >=20 > > +#define __gicv3_prio_to_ns(p) (0xff & ((p) << 1)) > > +#define __gicv3_ns_to_prio(ns) (0x80 | ((ns) >> 1)) >=20 > What about refactoring the gic_has_group0() using the mapping macros > between PMR priority and GIC priority like this: >=20 > ---------------%<----------------- > --- a/drivers/irqchip/irq-gic-v3.c > +++ b/drivers/irqchip/irq-gic-v3.c > @@ -882,6 +882,7 @@ static bool gic_has_group0(void) > { > u32 val; > u32 old_pmr; > + u32 prio =3D BIT(8 - gic_get_pribits()); >=20 > old_pmr =3D gic_read_pmr(); >=20 > @@ -896,12 +897,12 @@ static bool gic_has_group0(void) > * becomes 0x80. Reading it back returns 0, indicating that > * we're don't have access to Group0. > */ > - gic_write_pmr(BIT(8 - gic_get_pribits())); > + gic_write_pmr(prio); > val =3D gic_read_pmr(); >=20 > gic_write_pmr(old_pmr); >=20 > - return val !=3D 0; > + return val !=3D (__gicv3_prio_to_ns(__gicv3_ns_to_prio(prio))); > } > --------------->%----------------- No, that's terrible, and makes it simply impossible to understand what is happening without looking at 3 layers of indirection. Read the comment, and realise that the code implements exactly that. M. --=20 Without deviation from the norm, progress is not possible.