Hi Aidan,
Le lun., avril 11 2022 at 16:42:41 +0100, Aidan MacDonald
<aidanmacdonald.0x0@xxxxxxxxx> a écrit :
> The TCU clock gate on X1000 wasn't requested by the driver and
could
> be gated automatically later on in boot, which prevents timers
from
> running and breaks PWM.
>
> Add a workaround to support old device trees that don't specify
the
> "tcu" clock gate. In this case the kernel will print a warning and
> attempt to continue without the clock, which is wrong, but it
could
> work if "clk_ignore_unused" is in the kernel arguments.
>
> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@xxxxxxxxx>
> ---
> drivers/clk/ingenic/tcu.c | 38
++++++++++++++++++++++++++------------
> 1 file changed, 26 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/clk/ingenic/tcu.c b/drivers/clk/ingenic/tcu.c
> index 77acfbeb4830..ce8c768db997 100644
> --- a/drivers/clk/ingenic/tcu.c
> +++ b/drivers/clk/ingenic/tcu.c
> @@ -31,6 +31,7 @@ struct ingenic_soc_info {
> unsigned int num_channels;
> bool has_ost;
> bool has_tcu_clk;
> + bool allow_missing_tcu_clk;
> };
>
> struct ingenic_tcu_clk_info {
> @@ -320,7 +321,8 @@ static const struct ingenic_soc_info
> jz4770_soc_info = {
> static const struct ingenic_soc_info x1000_soc_info = {
> .num_channels = 8,
> .has_ost = false, /* X1000 has OST, but it not belong TCU */
> - .has_tcu_clk = false,
> + .has_tcu_clk = true,
> + .allow_missing_tcu_clk = true,
> };
>
> static const struct of_device_id __maybe_unused
> ingenic_tcu_of_match[] __initconst = {
> @@ -354,15 +356,27 @@ static int __init ingenic_tcu_probe(struct
> device_node *np)
> if (tcu->soc_info->has_tcu_clk) {
> tcu->clk = of_clk_get_by_name(np, "tcu");
> if (IS_ERR(tcu->clk)) {
> - ret = PTR_ERR(tcu->clk);
> - pr_crit("Cannot get TCU clock\n");
> - goto err_free_tcu;
> - }
> -
> - ret = clk_prepare_enable(tcu->clk);
> - if (ret) {
> - pr_crit("Unable to enable TCU clock\n");
> - goto err_put_clk;
> + /*
> + * Old device trees for some SoCs did not include the
> + * TCU clock because this driver (incorrectly) didn't
> + * use it. In this case we complain loudly and attempt
> + * to continue without the clock, which might work if
> + * booting with workarounds like "clk_ignore_unused".
> + */
Why not unconditionally enable it instead? Then it would boot
without
clk_ignore_unused.
Cheers,
-Paul
