From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932508AbaEGJhg (ORCPT ); Wed, 7 May 2014 05:37:36 -0400 Received: from fw-tnat.austin.arm.com ([217.140.110.23]:21408 "EHLO collaborate-mta1.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932069AbaEGJhf (ORCPT ); Wed, 7 May 2014 05:37:35 -0400 From: Marc Zyngier To: Feng Kan Cc: "tglx\@linutronix.de" , Catalin Marinas , Will Deacon , "linux-kernel\@vger.kernel.org" , "patches\@apm.com" , Vinayak Kale Subject: Re: [PATCH V4] gic: preserve gic V2 bypass bits in cpu ctrl register In-Reply-To: <1399424025-4199-1-git-send-email-fkan@apm.com> (Feng Kan's message of "Wed, 7 May 2014 01:53:45 +0100") Organization: ARM Ltd References: <1399424025-4199-1-git-send-email-fkan@apm.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) Date: Wed, 07 May 2014 10:37:26 +0100 Message-ID: <877g5yorop.fsf@approximate.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 07 2014 at 1:53:45 am BST, Feng Kan wrote: > This change is made to preserve the GIC v2 bypass bits in the > GIC_CPU_CTRL register (also known as the GICC_CTLR register in spec). > This code will preserve all bits configured by the bootload regarding bootloader > v2 bypass group bits. In the X-Gene platform (as well others), the Which other platform? It'd be interesting to know which one, as you're implying they haven't managed to boot a mainline kernel so far... > bypass functionality is not generally used and bypass bits should not > be changed by the kernel gic code as it could lead to incorrect behavior. > Tested on X-Gene mustang board. > > Signed-off-by: Vinayak Kale > Acked-by: Anup Patel > Signed-off-by: Feng Kan > --- > V4: Change to use bypass mask, change to use more suitable variable name. > V3: Fix code not touch other bits other than bypass bits. > > drivers/irqchip/irq-gic.c | 20 +++++++++++++++++--- > 1 files changed, 17 insertions(+), 3 deletions(-) > > diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c > index 4300b66..50a7bb2 100644 > --- a/drivers/irqchip/irq-gic.c > +++ b/drivers/irqchip/irq-gic.c > @@ -97,6 +97,8 @@ struct irq_chip gic_arch_extn = { > #define MAX_GIC_NR 1 > #endif > > +#define GIC_BYPASS_MASK 0x1e0 > + > static struct gic_chip_data gic_data[MAX_GIC_NR] __read_mostly; > > #ifdef CONFIG_GIC_NON_BANKED > @@ -418,6 +420,7 @@ static void gic_cpu_init(struct gic_chip_data *gic) > void __iomem *dist_base = gic_data_dist_base(gic); > void __iomem *base = gic_data_cpu_base(gic); > unsigned int cpu_mask, cpu = smp_processor_id(); > + unsigned int bypass; Please use a type that corresponds to the width of the access (u32 in this case). > int i; > > /* > @@ -449,13 +452,20 @@ static void gic_cpu_init(struct gic_chip_data *gic) > writel_relaxed(0xa0a0a0a0, dist_base + GIC_DIST_PRI + i * 4 / 4); > > writel_relaxed(0xf0, base + GIC_CPU_PRIMASK); > - writel_relaxed(1, base + GIC_CPU_CTRL); > + > + bypass = readl(base + GIC_CPU_CTRL); > + bypass &= GIC_BYPASS_MASK; > + writel_relaxed(bypass | 0x1, base + GIC_CPU_CTRL); > } > > void gic_cpu_if_down(void) > { > void __iomem *cpu_base = gic_data_cpu_base(&gic_data[0]); > - writel_relaxed(0, cpu_base + GIC_CPU_CTRL); > + unsigned int bypass; > + > + bypass = readl(cpu_base + GIC_CPU_CTRL); > + bypass &= GIC_BYPASS_MASK; > + writel_relaxed(bypass, cpu_base + GIC_CPU_CTRL); > } > > #ifdef CONFIG_CPU_PM > @@ -566,6 +576,7 @@ static void gic_cpu_restore(unsigned int gic_nr) > { > int i; > u32 *ptr; > + unsigned int bypass; > void __iomem *dist_base; > void __iomem *cpu_base; > > @@ -590,7 +601,10 @@ static void gic_cpu_restore(unsigned int gic_nr) > writel_relaxed(0xa0a0a0a0, dist_base + GIC_DIST_PRI + i * 4); > > writel_relaxed(0xf0, cpu_base + GIC_CPU_PRIMASK); > - writel_relaxed(1, cpu_base + GIC_CPU_CTRL); > + > + bypass = readl(cpu_base + GIC_CPU_CTRL); > + bypass &= GIC_BYPASS_MASK; > + writel_relaxed(bypass | 0x1, cpu_base + GIC_CPU_CTRL); It would be good to turn these into a static function (gic_cpu_if_up, matching gic_cpu_if_down?), and use it in both gic_cpu_init and gic_cpu_restore. Thanks, M. -- Jazz is not dead. It just smells funny.