[PATCH] clocksource/drivers/timer-mediatek: initialize GPT6 as system counter

[Akari Tsuyukusa]

On Thu, Mar 26, 2026 at 10:00 AM Roman Vivchar via B4 Relay
<devnull+rva333.protonmail.com at kernel.org> wrote:
> On certain MediaTek SoCs like mt6572 (likely before the CPUXGPT was
> introduced), the generic arch timer is fed by the GPT6. Some bootloaders
> don't initialize it properly, leading to dead arch timer.
>
> Fix this by configuring GPT6 when the MediaTek timer is probed. This
> makes arch timer work properly and removes IPI overhead from MediaTek
> timer broadcast when arch timer is used.
>
> If the timer was configured by the bootloader, this change is no-op.
>
> Tested-by: Akari Tsuyukusa <akkun11.open at gmail.com> # MT6589
> Signed-off-by: Roman Vivchar <rva333 at protonmail.com>
> ---
>  drivers/clocksource/timer-mediatek.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/clocksource/timer-mediatek.c b/drivers/clocksource/timer-mediatek.c
> index 7bcb4a3f26fb..7de34cace572 100644
> --- a/drivers/clocksource/timer-mediatek.c
> +++ b/drivers/clocksource/timer-mediatek.c
> @@ -22,6 +22,8 @@
>
>  #define TIMER_SYNC_TICKS        (3)
>
> +#define TIMER_SYSCNT            (6)
> +
>  /* gpt */
>  #define GPT_IRQ_EN_REG          0x00
>  #define GPT_IRQ_ENABLE(val)     BIT((val) - 1)
> @@ -335,6 +337,9 @@ static int __init mtk_gpt_init(struct device_node *node)
>
>         mtk_gpt_enable_irq(&to, TIMER_CLK_EVT);
>
> +       /* Configure GPT6 to feed arch timer */
> +       mtk_gpt_setup(&to, TIMER_SYSCNT, GPT_CTRL_OP_FREERUN);
> +
>         return 0;
>  }
>  TIMER_OF_DECLARE(mtk_mt6577, "mediatek,mt6577-timer", mtk_gpt_init);
>
> ---

Although it has already been written,
I tested this patch on MT6589 (Lenovo YOGA Tablet 10 Wi-Fi),
and I have confirmed that MediaTek's timer and Arm Generic Timer are
working properly as before the patch was applied.
Therefore,

Tested-by: Akari Tsuyukusa <akkun11.open at gmail.com>

Best regards,
Akari Tsuyukusa