On 14.05.2020 13:30, Vincent Whitchurch wrote:
> If adv7511's devm_clk_get() for the cec clock returns -EPROBE_DEFER, we
> end up in an infinite probe loop. This happens:
>
> (1) adv7511's probe is called.
>
> (2) adv7511's probe adds some secondary i2c devices which bind to the
> dummy driver and thus call driver_deferred_probe_trigger() and
> increment deferred_trigger_count (see driver_bound()).
>
> (3) adv7511's probe returns -EPROBE_DEFER, and since the
> deferred_trigger_count has changed during the probe call,
> driver_deferred_probe_trigger() is called immediately (see
> really_probe()) and adv7511's probe is scheduled.
>
> (4) Goto step 1.
>
> [ 61.972915] really_probe: bus: 'i2c': really_probe: probing driver adv7511 with device 0-0039
> [ 61.992734] really_probe: bus: 'i2c': really_probe: probing driver dummy with device 0-003f
> [ 61.993343] driver_bound: driver: 'dummy': driver_bound: bound to device '0-003f'
> [ 61.993626] really_probe: bus: 'i2c': really_probe: bound device 0-003f to driver dummy
> [ 61.995604] really_probe: bus: 'i2c': really_probe: probing driver dummy with device 0-0038
> [ 61.996381] driver_bound: driver: 'dummy': driver_bound: bound to device '0-0038'
> [ 61.996663] really_probe: bus: 'i2c': really_probe: bound device 0-0038 to driver dummy
> [ 61.998651] really_probe: bus: 'i2c': really_probe: probing driver dummy with device 0-003c
> [ 61.999222] driver_bound: driver: 'dummy': driver_bound: bound to device '0-003c'
> [ 61.999496] really_probe: bus: 'i2c': really_probe: bound device 0-003c to driver dummy
> [ 62.010050] really_probe: i2c 0-0039: Driver adv7511 requests probe deferral
> [ 62.011380] really_probe: bus: 'platform': really_probe: probing driver pwm-clock with device clock-cec
> [ 62.012812] really_probe: platform clock-cec: Driver pwm-clock requests probe deferral
> [ 62.024679] really_probe: bus: 'i2c': really_probe: probing driver adv7511 with device 0-0039
>
> Fix this by calling devm_clk_get() before registering the secondary
> devices.
>
> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx>
> ---
> v3: Make adv7511_cec_init() return void.
> v2: Add devm_clk_put() in error path.
>
> drivers/gpu/drm/bridge/adv7511/adv7511.h | 5 ++-
> drivers/gpu/drm/bridge/adv7511/adv7511_cec.c | 34 ++++++++------------
> drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 15 ++++++---
> 3 files changed, 25 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511.h b/drivers/gpu/drm/bridge/adv7511/adv7511.h
> index a9bb734366ae..05a66149b186 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7511.h
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511.h
> @@ -380,17 +380,16 @@ struct adv7511 {
> };
>
> #ifdef CONFIG_DRM_I2C_ADV7511_CEC
> -int adv7511_cec_init(struct device *dev, struct adv7511 *adv7511);
> +void adv7511_cec_init(struct device *dev, struct adv7511 *adv7511);
> void adv7511_cec_irq_process(struct adv7511 *adv7511, unsigned int irq1);
> #else
> -static inline int adv7511_cec_init(struct device *dev, struct adv7511 *adv7511)
> +static inline void adv7511_cec_init(struct device *dev, struct adv7511 *adv7511)
> {
> unsigned int offset = adv7511->type == ADV7533 ?
> ADV7533_REG_CEC_OFFSET : 0;
>
> regmap_write(adv7511->regmap, ADV7511_REG_CEC_CTRL + offset,
> ADV7511_CEC_CTRL_POWER_DOWN);
> - return 0;
> }
> #endif
>
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c b/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c
> index a20a45c0b353..ee0ed4fb67c1 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c
> @@ -286,28 +286,17 @@ static const struct cec_adap_ops adv7511_cec_adap_ops = {
> .adap_transmit = adv7511_cec_adap_transmit,
> };
>
> -static int adv7511_cec_parse_dt(struct device *dev, struct adv7511 *adv7511)
> -{
> - adv7511->cec_clk = devm_clk_get(dev, "cec");
> - if (IS_ERR(adv7511->cec_clk)) {
> - int ret = PTR_ERR(adv7511->cec_clk);
> -
> - adv7511->cec_clk = NULL;
> - return ret;
> - }
> - clk_prepare_enable(adv7511->cec_clk);
> - adv7511->cec_clk_freq = clk_get_rate(adv7511->cec_clk);
> - return 0;
> -}
> -
> -int adv7511_cec_init(struct device *dev, struct adv7511 *adv7511)
> +void adv7511_cec_init(struct device *dev, struct adv7511 *adv7511)
> {
> unsigned int offset = adv7511->type == ADV7533 ?
> ADV7533_REG_CEC_OFFSET : 0;
> - int ret = adv7511_cec_parse_dt(dev, adv7511);
> + int ret;
>
> - if (ret)
> - goto err_cec_parse_dt;
> + if (!adv7511->cec_clk)
> + goto err_cec_no_clock;
> +
> + clk_prepare_enable(adv7511->cec_clk);
> + adv7511->cec_clk_freq = clk_get_rate(adv7511->cec_clk);
>
> adv7511->cec_adap = cec_allocate_adapter(&adv7511_cec_adap_ops,
> adv7511, dev_name(dev), CEC_CAP_DEFAULTS, ADV7511_MAX_ADDRS);
> @@ -334,7 +323,7 @@ int adv7511_cec_init(struct device *dev, struct adv7511 *adv7511)
> ret = cec_register_adapter(adv7511->cec_adap, dev);
> if (ret)
> goto err_cec_register;
> - return 0;
> + return;
>
> err_cec_register:
> cec_delete_adapter(adv7511->cec_adap);
> @@ -342,8 +331,11 @@ int adv7511_cec_init(struct device *dev, struct adv7511 *adv7511)
> err_cec_alloc:
> dev_info(dev, "Initializing CEC failed with error %d, disabling CEC\n",
> ret);
> -err_cec_parse_dt:
> + clk_disable_unprepare(adv7511->cec_clk);
> + devm_clk_put(dev, adv7511->cec_clk);
> + /* Ensure that adv7511_remove() doesn't attempt to disable it again. */
> + adv7511->cec_clk = NULL;
Are you sure these three lines above are necessary? devm mechanism
should free the clock and with failed probe remove should not be called.
Beside this:
Reviewed-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
Regards
Andrzej
> +err_cec_no_clock:
> regmap_write(adv7511->regmap, ADV7511_REG_CEC_CTRL + offset,
> ADV7511_CEC_CTRL_POWER_DOWN);
> - return ret == -EPROBE_DEFER ? ret : 0;
> }
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> index 87b58c1acff4..8d8df6116082 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> @@ -1128,6 +1128,15 @@ static int adv7511_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
> if (ret)
> return ret;
>
> + adv7511->cec_clk = devm_clk_get(dev, "cec");
> + if (IS_ERR(adv7511->cec_clk)) {
> + ret = PTR_ERR(adv7511->cec_clk);
> + if (ret == -EPROBE_DEFER)
> + return ret;
> +
> + adv7511->cec_clk = NULL;
> + }
> +
> ret = adv7511_init_regulators(adv7511);
> if (ret) {
> dev_err(dev, "failed to init regulators\n");
> @@ -1218,9 +1227,7 @@ static int adv7511_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
> if (adv7511->type == ADV7511)
> adv7511_set_link_config(adv7511, &link_config);
>
> - ret = adv7511_cec_init(dev, adv7511);
> - if (ret)
> - goto err_unregister_cec;
> + adv7511_cec_init(dev, adv7511);
>
> adv7511->bridge.funcs = &adv7511_bridge_funcs;
> adv7511->bridge.of_node = dev->of_node;
> @@ -1232,8 +1239,6 @@ static int adv7511_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
>
> err_unregister_cec:
> i2c_unregister_device(adv7511->i2c_cec);
> - if (adv7511->cec_clk)
> - clk_disable_unprepare(adv7511->cec_clk);
> err_i2c_unregister_packet:
> i2c_unregister_device(adv7511->i2c_packet);
> err_i2c_unregister_edid:
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