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SubjectRe: [PATCH 3/3] arm: zynq: slcr: Use read-modify-write for register writes
On Thu, Jul 18, 2013 at 09:21:06AM +0200, Steffen Trumtrar wrote:
> On Wed, Jul 17, 2013 at 10:10:15AM -0700, Sören 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 <soren.brinkmann@xilinx.com>
> > ---
> > 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.
I found the #defines descriptive enough

Sören


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