On Mon, Jan 18, 2021 at 08:44:42AM +0800, Weijie Gao wrote: > On Fri, 2021-01-15 at 17:36 +0100, Matthias Brugger wrote: > > On Tue, Jan 12, 2021 at 01:44:02PM +0800, Weijie Gao wrote: > > > The timer being used by this driver may have already been used by first > > > stage bootloader (e.g. ATF/preloader), and it's settings may differ from > > > what this driver is going to use. > > > > > > This may cause issues, such as inaccurate timer frequency due to > > > incorrect clock divider. > > > > > > This patch adds the initialization code to avoid them. > > > > > > Signed-off-by: Weijie Gao <weijie....@mediatek.com> > > > --- > > > drivers/timer/mtk_timer.c | 10 ++++++++++ > > > 1 file changed, 10 insertions(+) > > > > > > diff --git a/drivers/timer/mtk_timer.c b/drivers/timer/mtk_timer.c > > > index 448a76a7e1..f6b97f868c 100644 > > > --- a/drivers/timer/mtk_timer.c > > > +++ b/drivers/timer/mtk_timer.c > > > @@ -61,6 +61,16 @@ static int mtk_timer_probe(struct udevice *dev) > > > if (!uc_priv->clock_rate) > > > return -EINVAL; > > > > > > + /* > > > + * Initialize the timer: > > > + * 1. set clock source to system clock with clock divider setting to 1 > > > + * 2. set timer mode to free running > > > + * 3. reset timer counter to 0 then enable the timer > > > + */ > > > + writel(GPT4_CLK_SYS | GPT4_CLK_DIV1, priv->base + MTK_GPT4_CLK); > > > + writel(GPT4_FREERUN | GPT4_CLEAR | GPT4_ENABLE, > > > > GPT4_FREERUN is defined as GENMASK(5,4) while in the Linux kernel it has > > the value of 3. Can you explain where this difference comes from? > > GENMASK(5,4) == 3 << 4, which is exactly the same as what's being used > in kernel: > > #define GPT_CTRL_OP(val) (((val) & 0x3) << 4) > #define GPT_CTRL_OP_FREERUN (3) >
You are right, sorry my fault: Reviewed-by: Matthias Brugger <matthias....@gmail.com> > > > > Regards, > > Matthias > > > > > + priv->base + MTK_GPT4_CTRL); > > > + > > > return 0; > > > } > > > > > > -- > > > 2.17.1 >
