From mboxrd@z Thu Jan 1 00:00:00 1970 From: s.trumtrar@pengutronix.de (Steffen Trumtrar) Date: Thu, 18 Jul 2013 09:21:06 +0200 Subject: [PATCH 3/3] arm: zynq: slcr: Use read-modify-write for register writes In-Reply-To: <1374081015-31431-4-git-send-email-soren.brinkmann@xilinx.com> References: <1374081015-31431-1-git-send-email-soren.brinkmann@xilinx.com> <1374081015-31431-4-git-send-email-soren.brinkmann@xilinx.com> Message-ID: <20130718072106.GB15514@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Jul 17, 2013 at 10:10:15AM -0700, S?ren Brinkmann wrote: > zynq_slcr_cpu_start/stop() ignored the current register state when > writing to a register. Fixing this by implementing proper > read-modify-write. > > Signed-off-by: Soren Brinkmann > --- > arch/arm/mach-zynq/slcr.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/arch/arm/mach-zynq/slcr.c b/arch/arm/mach-zynq/slcr.c > index 44a4ab6..1836d5a 100644 > --- a/arch/arm/mach-zynq/slcr.c > +++ b/arch/arm/mach-zynq/slcr.c > @@ -61,11 +61,11 @@ void zynq_slcr_system_reset(void) > */ > void zynq_slcr_cpu_start(int cpu) > { > - /* enable CPUn */ > - writel(SLCR_A9_CPU_CLKSTOP << cpu, > - zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET); > - /* enable CLK for CPUn */ > - writel(0x0 << cpu, zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET); > + u32 reg = readl(zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET); > + reg &= ~(SLCR_A9_CPU_RST << cpu); > + writel(reg, zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET); > + reg &= ~(SLCR_A9_CPU_CLKSTOP << cpu); > + writel(reg, zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET); > } > > /** > @@ -74,9 +74,9 @@ void zynq_slcr_cpu_start(int cpu) > */ > void zynq_slcr_cpu_stop(int cpu) > { > - /* stop CLK and reset CPUn */ > - writel((SLCR_A9_CPU_CLKSTOP | SLCR_A9_CPU_RST) << cpu, > - zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET); > + u32 reg = readl(zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET); > + reg |= (SLCR_A9_CPU_CLKSTOP | SLCR_A9_CPU_RST) << cpu; > + writel(reg, zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET); > } > Hi! Why do you also remove the comments? In my opinion they can stay. Regards, Steffen -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |