Re: [PATCH v2] pmdomain: mediatek: Fix mt8183 hang on boot

[Ulf Hansson]

On Wed, Jul 29, 2026 at 3:00 PM Dmitry Osipenko
<dmitry.osipenko@xxxxxxxxxxxxx> wrote:
>
> Depending on firmware, part of the MFG domains may be partially left ON
> at boot time with kernel detecting PD as ON, while it's OFF.
>
> Some of MFG cores may be left powered after bootloader, to let the ACP to
> prefetch the GPU region when the display controller is brought up for a
> continuous splash animation performed by downstream stack.
>
> This doesn't play well with an eventual delay in probing upstream Panfrost
> driver when the display controller is fully set up, as that would make
> genpd's sync_state() to power off the domain while ACP tries to prefetch:
> this is causing an AXI stall, effectively freezing the AP indefinitely.
>
> In order to prevent trouble from happening, the sync_state() functionality
> must be obliterated on all of the MFG domains: while this guarantees a
> power leakage if the bootloader boots the kernel with MFG PDs partially
> powered on, this is the only way to ensure stable operation of the SoC
> during boot on devices with such firmware because, of course, those will
> never officially receive a firmware update.
>
> Fixes Kappa Chromebook hanging during system boot.
>
> Fixes: 0e789b491ba0 ("pmdomain: core: Leave powered-on genpds on until sync_state")
> Fixes: 13a4b7fb6260 ("pmdomain: core: Leave powered-on genpds on until late_initcall_sync")
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>

Applied for fixes and by adding a stable tag, thanks!

Kind regards
Uffe


> ---
>
> v2 - Expanded commit message with more clarification about kernel wrongly
>      detecting PD state left after bootloader.
>
>  drivers/pmdomain/mediatek/mt8183-pm-domains.h | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pmdomain/mediatek/mt8183-pm-domains.h b/drivers/pmdomain/mediatek/mt8183-pm-domains.h
> index 3742782a2702..5e33b8628e85 100644
> --- a/drivers/pmdomain/mediatek/mt8183-pm-domains.h
> +++ b/drivers/pmdomain/mediatek/mt8183-pm-domains.h
> @@ -47,7 +47,7 @@ static const struct scpsys_domain_data scpsys_domain_data_mt8183[] = {
>                 .pwr_sta2nd_offs = 0x0184,
>                 .sram_pdn_bits = 0,
>                 .sram_pdn_ack_bits = 0,
> -               .caps = MTK_SCPD_DOMAIN_SUPPLY,
> +               .caps = MTK_SCPD_DOMAIN_SUPPLY | MTK_SCPD_KEEP_DEFAULT_OFF,
>         },
>         [MT8183_POWER_DOMAIN_MFG] = {
>                 .name = "mfg",
> @@ -57,7 +57,7 @@ static const struct scpsys_domain_data scpsys_domain_data_mt8183[] = {
>                 .pwr_sta2nd_offs = 0x0184,
>                 .sram_pdn_bits = GENMASK(8, 8),
>                 .sram_pdn_ack_bits = GENMASK(12, 12),
> -               .caps = MTK_SCPD_DOMAIN_SUPPLY,
> +               .caps = MTK_SCPD_DOMAIN_SUPPLY | MTK_SCPD_KEEP_DEFAULT_OFF,
>         },
>         [MT8183_POWER_DOMAIN_MFG_CORE0] = {
>                 .name = "mfg_core0",
> @@ -67,6 +67,7 @@ static const struct scpsys_domain_data scpsys_domain_data_mt8183[] = {
>                 .pwr_sta2nd_offs = 0x0184,
>                 .sram_pdn_bits = GENMASK(8, 8),
>                 .sram_pdn_ack_bits = GENMASK(12, 12),
> +               .caps = MTK_SCPD_KEEP_DEFAULT_OFF,
>         },
>         [MT8183_POWER_DOMAIN_MFG_CORE1] = {
>                 .name = "mfg_core1",
> @@ -76,6 +77,7 @@ static const struct scpsys_domain_data scpsys_domain_data_mt8183[] = {
>                 .pwr_sta2nd_offs = 0x0184,
>                 .sram_pdn_bits = GENMASK(8, 8),
>                 .sram_pdn_ack_bits = GENMASK(12, 12),
> +               .caps = MTK_SCPD_KEEP_DEFAULT_OFF,
>         },
>         [MT8183_POWER_DOMAIN_MFG_2D] = {
>                 .name = "mfg_2d",
> @@ -85,6 +87,7 @@ static const struct scpsys_domain_data scpsys_domain_data_mt8183[] = {
>                 .pwr_sta2nd_offs = 0x0184,
>                 .sram_pdn_bits = GENMASK(8, 8),
>                 .sram_pdn_ack_bits = GENMASK(12, 12),
> +               .caps = MTK_SCPD_KEEP_DEFAULT_OFF,
>                 .bp_cfg = {
>                         BUS_PROT_WR(INFRA,
>                                     MT8183_TOP_AXI_PROT_EN_1_MFG,
> --
> 2.54.0
>