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Date:   Wed, 30 Dec 2020 06:55:37 -0600
From:   Adam Ford <aford173@...il.com>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Amit Kucheria <amitk@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Keerthy <j-keerthy@...com>, linux-pm@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux-OMAP <linux-omap@...r.kernel.org>,
        Carl Philipp Klemm <philipp@...s.xyz>,
        Merlijn Wajer <merlijn@...zup.org>,
        Pavel Machek <pavel@....cz>,
        Peter Ujfalusi <peter.ujfalusi@...il.com>,
        Sebastian Reichel <sre@...nel.org>
Subject: Re: [PATCH 1/3] thermal: ti-soc-thermal: Fix stuck sensor with
 continuous mode for 4430

On Wed, Dec 30, 2020 at 2:43 AM Tony Lindgren <tony@...mide.com> wrote:
>
> At least for 4430, trying to use the single conversion mode eventually
> hangs the thermal sensor. This can be quite easily seen with errors:
>
> thermal thermal_zone0: failed to read out thermal zone (-5)
>
> Also, trying to read the temperature shows a stuck value with:
>
> $ while true; do cat /sys/class/thermal/thermal_zone0/temp; done
>
> Where the temperature is not rising at all with the busy loop.
>
> Additionally, the EOCZ (end of conversion) bit is not rising on 4430 in
> single conversion mode while it works fine in continuous conversion mode.
> It is also possible that the hung temperature sensor can affect the
> thermal shutdown alert too.
>
> Let's fix the issue by adding TI_BANDGAP_FEATURE_CONT_MODE_ONLY flag and
> use it for 4430.
>
> Note that we also need to add udelay to for the EOCZ (end of conversion)
> bit polling as otherwise we have it time out too early on 4430. We'll be
> changing the loop to use iopoll in the following clean-up patch.
>
> Cc: Adam Ford <aford173@...il.com>

I don't have an OMAP4, but if you want, I can test a DM3730.

adam

> Cc: Carl Philipp Klemm <philipp@...s.xyz>
> Cc: Eduardo Valentin <edubezval@...il.com>
> Cc: Merlijn Wajer <merlijn@...zup.org>
> Cc: Pavel Machek <pavel@....cz>
> Cc: Peter Ujfalusi <peter.ujfalusi@...il.com>
> Cc: Sebastian Reichel <sre@...nel.org>
> Signed-off-by: Tony Lindgren <tony@...mide.com>
> ---
>  drivers/thermal/ti-soc-thermal/omap4-thermal-data.c | 3 ++-
>  drivers/thermal/ti-soc-thermal/ti-bandgap.c         | 9 +++++++--
>  drivers/thermal/ti-soc-thermal/ti-bandgap.h         | 2 ++
>  3 files changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/thermal/ti-soc-thermal/omap4-thermal-data.c b/drivers/thermal/ti-soc-thermal/omap4-thermal-data.c
> --- a/drivers/thermal/ti-soc-thermal/omap4-thermal-data.c
> +++ b/drivers/thermal/ti-soc-thermal/omap4-thermal-data.c
> @@ -58,7 +58,8 @@ omap4430_adc_to_temp[OMAP4430_ADC_END_VALUE - OMAP4430_ADC_START_VALUE + 1] = {
>  const struct ti_bandgap_data omap4430_data = {
>         .features = TI_BANDGAP_FEATURE_MODE_CONFIG |
>                         TI_BANDGAP_FEATURE_CLK_CTRL |
> -                       TI_BANDGAP_FEATURE_POWER_SWITCH,
> +                       TI_BANDGAP_FEATURE_POWER_SWITCH |
> +                       TI_BANDGAP_FEATURE_CONT_MODE_ONLY,
>         .fclock_name = "bandgap_fclk",
>         .div_ck_name = "bandgap_fclk",
>         .conv_table = omap4430_adc_to_temp,
> diff --git a/drivers/thermal/ti-soc-thermal/ti-bandgap.c b/drivers/thermal/ti-soc-thermal/ti-bandgap.c
> --- a/drivers/thermal/ti-soc-thermal/ti-bandgap.c
> +++ b/drivers/thermal/ti-soc-thermal/ti-bandgap.c
> @@ -15,6 +15,7 @@
>  #include <linux/kernel.h>
>  #include <linux/interrupt.h>
>  #include <linux/clk.h>
> +#include <linux/delay.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/platform_device.h>
>  #include <linux/err.h>
> @@ -605,8 +606,10 @@ ti_bandgap_force_single_read(struct ti_bandgap *bgp, int id)
>         u32 counter = 1000;
>         struct temp_sensor_registers *tsr;
>
> -       /* Select single conversion mode */
> -       if (TI_BANDGAP_HAS(bgp, MODE_CONFIG))
> +       /* Select continuous or single conversion mode */
> +       if (TI_BANDGAP_HAS(bgp, CONT_MODE_ONLY))
> +               RMW_BITS(bgp, id, bgap_mode_ctrl, mode_ctrl_mask, 1);
> +       else if (TI_BANDGAP_HAS(bgp, MODE_CONFIG))
>                 RMW_BITS(bgp, id, bgap_mode_ctrl, mode_ctrl_mask, 0);
>
>         /* Start of Conversion = 1 */
> @@ -619,6 +622,7 @@ ti_bandgap_force_single_read(struct ti_bandgap *bgp, int id)
>                 if (ti_bandgap_readl(bgp, tsr->temp_sensor_ctrl) &
>                     tsr->bgap_eocz_mask)
>                         break;
> +               udelay(1);
>         }
>
>         /* Start of Conversion = 0 */
> @@ -630,6 +634,7 @@ ti_bandgap_force_single_read(struct ti_bandgap *bgp, int id)
>                 if (!(ti_bandgap_readl(bgp, tsr->temp_sensor_ctrl) &
>                       tsr->bgap_eocz_mask))
>                         break;
> +               udelay(1);
>         }
>
>         return 0;
> diff --git a/drivers/thermal/ti-soc-thermal/ti-bandgap.h b/drivers/thermal/ti-soc-thermal/ti-bandgap.h
> --- a/drivers/thermal/ti-soc-thermal/ti-bandgap.h
> +++ b/drivers/thermal/ti-soc-thermal/ti-bandgap.h
> @@ -280,6 +280,7 @@ struct ti_temp_sensor {
>   *     has Errata 814
>   * TI_BANDGAP_FEATURE_UNRELIABLE - used when the sensor readings are too
>   *     inaccurate.
> + * TI_BANDGAP_FEATURE_CONT_MODE_ONLY - used when single mode hangs the sensor
>   * TI_BANDGAP_HAS(b, f) - macro to check if a bandgap device is capable of a
>   *      specific feature (above) or not. Return non-zero, if yes.
>   */
> @@ -295,6 +296,7 @@ struct ti_temp_sensor {
>  #define TI_BANDGAP_FEATURE_HISTORY_BUFFER      BIT(9)
>  #define TI_BANDGAP_FEATURE_ERRATA_814          BIT(10)
>  #define TI_BANDGAP_FEATURE_UNRELIABLE          BIT(11)
> +#define TI_BANDGAP_FEATURE_CONT_MODE_ONLY      BIT(12)
>  #define TI_BANDGAP_HAS(b, f)                   \
>                         ((b)->conf->features & TI_BANDGAP_FEATURE_ ## f)
>
> --
> 2.29.2

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