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Message-ID: <f2q5u6hhzer4wwyz6c7kzrm6i6az5l6dhlfshuirwmhvps4z5g@sx53vb4wbpr5>
Date: Wed, 29 Jan 2025 14:57:53 -0600
From: Bjorn Andersson <andersson@...nel.org>
To: Abel Vesa <abel.vesa@...aro.org>
Cc: Konrad Dybcio <konradybcio@...nel.org>,
Caleb Connolly <caleb.connolly@...aro.org>, Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
Johan Hovold <johan@...nel.org>, Neil Armstrong <neil.armstrong@...aro.org>,
linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
Johan Hovold <johan+linaro@...nel.org>, stable@...r.kernel.org
Subject: Re: [PATCH RFC v2] soc: qcom: pmic_glink: Fix device access from
worker during suspend
On Wed, Jan 29, 2025 at 01:46:15PM +0200, Abel Vesa wrote:
> For historical reasons, the GLINK smem interrupt is registered with
> IRRQF_NO_SUSPEND flag set, which is the underlying problem here, since the
> incoming messages can be delivered during late suspend and early
> resume.
>
> In this specific case, the pmic_glink_altmode_worker() currently gets
> scheduled on the system_wq which can be scheduled to run while devices
> are still suspended. This proves to be a problem when a Type-C retimer,
> switch or mux that is controlled over a bus like I2C, because the I2C
> controller is suspended.
>
> This has been proven to be the case on the X Elite boards where such
> retimers (ParadeTech PS8830) are used in order to handle Type-C
> orientation and altmode configuration. The following warning is thrown:
>
> [ 35.134876] i2c i2c-4: Transfer while suspended
> [ 35.143865] WARNING: CPU: 0 PID: 99 at drivers/i2c/i2c-core.h:56 __i2c_transfer+0xb4/0x57c [i2c_core]
> [ 35.352879] Workqueue: events pmic_glink_altmode_worker [pmic_glink_altmode]
> [ 35.360179] pstate: 61400005 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
> [ 35.455242] Call trace:
> [ 35.457826] __i2c_transfer+0xb4/0x57c [i2c_core] (P)
> [ 35.463086] i2c_transfer+0x98/0xf0 [i2c_core]
> [ 35.467713] i2c_transfer_buffer_flags+0x54/0x88 [i2c_core]
> [ 35.473502] regmap_i2c_write+0x20/0x48 [regmap_i2c]
> [ 35.478659] _regmap_raw_write_impl+0x780/0x944
> [ 35.483401] _regmap_bus_raw_write+0x60/0x7c
> [ 35.487848] _regmap_write+0x134/0x184
> [ 35.491773] regmap_write+0x54/0x78
> [ 35.495418] ps883x_set+0x58/0xec [ps883x]
> [ 35.499688] ps883x_sw_set+0x60/0x84 [ps883x]
> [ 35.504223] typec_switch_set+0x48/0x74 [typec]
> [ 35.508952] pmic_glink_altmode_worker+0x44/0x1fc [pmic_glink_altmode]
> [ 35.515712] process_scheduled_works+0x1a0/0x2d0
> [ 35.520525] worker_thread+0x2a8/0x3c8
> [ 35.524449] kthread+0xfc/0x184
> [ 35.527749] ret_from_fork+0x10/0x20
>
> The proper solution here should be to not deliver these kind of messages
> during system suspend at all, or at least make it configurable per glink
> client. But simply dropping the IRQF_NO_SUSPEND flag entirely will break
> other clients. The final shape of the rework of the pmic glink driver in
> order to fulfill both the filtering of the messages that need to be able
> to wake-up the system and the queueing of these messages until the system
> has properly resumed is still being discussed and it is planned as a
> future effort.
>
> Meanwhile, the stop-gap fix here is to schedule the pmic glink altmode
> worker on the system_freezable_wq instead of the system_wq. This will
> result in the altmode worker not being scheduled to run until the
> devices are resumed first, which will give the controllers like I2C a
> chance to resume before the transfer is requested.
>
> Reported-by: Johan Hovold <johan+linaro@...nel.org>
> Closes: https://lore.kernel.org/lkml/Z1CCVjEZMQ6hJ-wK@hovoldconsulting.com/
> Fixes: 080b4e24852b ("soc: qcom: pmic_glink: Introduce altmode support")
> Cc: stable@...r.kernel.org # 6.3
> Reviewed-by: Caleb Connolly <caleb.connolly@...aro.org>
> Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
Reviewed-by: Bjorn Andersson <andersson@...nel.org>
Regards,
Bjorn
> ---
> Changes in v2:
> - Re-worded the commit to explain the underlying problem and how
> this fix is just a stop-gap for the pmic glink client for now.
> - Added Johan's Reported-by tag and link
> - Added Caleb's Reviewed-by tag
> - Link to v1: https://lore.kernel.org/r/20250110-soc-qcom-pmic-glink-fix-device-access-on-worker-while-suspended-v1-1-e32fd6bf322e@linaro.org
> ---
> drivers/soc/qcom/pmic_glink_altmode.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/soc/qcom/pmic_glink_altmode.c b/drivers/soc/qcom/pmic_glink_altmode.c
> index bd06ce16180411059e9efb14d9aeccda27744280..bde129aa7d90a39becaa720376c0539bcaa492fb 100644
> --- a/drivers/soc/qcom/pmic_glink_altmode.c
> +++ b/drivers/soc/qcom/pmic_glink_altmode.c
> @@ -295,7 +295,7 @@ static void pmic_glink_altmode_sc8180xp_notify(struct pmic_glink_altmode *altmod
> alt_port->mode = mode;
> alt_port->hpd_state = hpd_state;
> alt_port->hpd_irq = hpd_irq;
> - schedule_work(&alt_port->work);
> + queue_work(system_freezable_wq, &alt_port->work);
> }
>
> #define SC8280XP_DPAM_MASK 0x3f
> @@ -338,7 +338,7 @@ static void pmic_glink_altmode_sc8280xp_notify(struct pmic_glink_altmode *altmod
> alt_port->mode = mode;
> alt_port->hpd_state = hpd_state;
> alt_port->hpd_irq = hpd_irq;
> - schedule_work(&alt_port->work);
> + queue_work(system_freezable_wq, &alt_port->work);
> }
>
> static void pmic_glink_altmode_callback(const void *data, size_t len, void *priv)
>
> ---
> base-commit: da7e6047a6264af16d2cb82bed9b6caa33eaf56a
> change-id: 20250110-soc-qcom-pmic-glink-fix-device-access-on-worker-while-suspended-af54c5e43ed6
>
> Best regards,
> --
> Abel Vesa <abel.vesa@...aro.org>
>
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