Re: [PATCH 2/2] thermal: ti-soc-thermal: OMAP5: Implement Workaround for Errata i813

[Eduardo Valentin <edubezval@gmail.com>]

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On Wed, Apr 22, 2015 at 06:21:42PM +0530, Keerthy wrote:
> DESCRIPTION
> 
> Spurious Thermal Alert: Talert can happen randomly while the device remains under the temperature limit
> defined for this event to trig. This spurious event is caused by a incorrect re-synchronization between
> clock domains. The comparison between configured threshold and current temperature value can happen
> while the value is transitioning (metastable), thus causing inappropriate event generation.
> No spurious event occurs as long as the threshold value stays unchanged. Spurious event can be
> generated while a thermal alert threshold is modified in
> CONTROL_BANDGAP_THRESHOLD_MPU/GPU/CORE/DSPEVE/IVA_n.
> WORKAROUND
> 
> Spurious event generation can be avoided by performing following sequence when the threshold is
> modified:
> 1. Mask the hot/cold events at the thermal IP level.
> 2. Modify Threshold.
> 3. Unmask the hot/cold events at the thermal IP level.
> 

applying to my -fixes branch. next time, please make sure you have the
correct linux-pm address so we can track the patch in our patchwork.

BR,

Eduardo Valentin

> Signed-off-by: Keerthy <j-keerthy@ti.com>
> ---
>  .../thermal/ti-soc-thermal/omap5-thermal-data.c    |  3 +-
>  drivers/thermal/ti-soc-thermal/ti-bandgap.c        | 41 +++++++++++++++++++++-
>  drivers/thermal/ti-soc-thermal/ti-bandgap.h        |  4 ++-
>  3 files changed, 45 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/thermal/ti-soc-thermal/omap5-thermal-data.c b/drivers/thermal/ti-soc-thermal/omap5-thermal-data.c
> index eff0c80..79ff70c 100644
> --- a/drivers/thermal/ti-soc-thermal/omap5-thermal-data.c
> +++ b/drivers/thermal/ti-soc-thermal/omap5-thermal-data.c
> @@ -319,7 +319,8 @@ const struct ti_bandgap_data omap5430_data = {
>  			TI_BANDGAP_FEATURE_FREEZE_BIT |
>  			TI_BANDGAP_FEATURE_TALERT |
>  			TI_BANDGAP_FEATURE_COUNTER_DELAY |
> -			TI_BANDGAP_FEATURE_HISTORY_BUFFER,
> +			TI_BANDGAP_FEATURE_HISTORY_BUFFER |
> +			TI_BANDGAP_FEATURE_ERRATA_813,
>  	.fclock_name = "l3instr_ts_gclk_div",
>  	.div_ck_name = "l3instr_ts_gclk_div",
>  	.conv_table = omap5430_adc_to_temp,
> diff --git a/drivers/thermal/ti-soc-thermal/ti-bandgap.c b/drivers/thermal/ti-soc-thermal/ti-bandgap.c
> index 8fdddb6..08a2155 100644
> --- a/drivers/thermal/ti-soc-thermal/ti-bandgap.c
> +++ b/drivers/thermal/ti-soc-thermal/ti-bandgap.c
> @@ -445,7 +445,7 @@ static int ti_bandgap_update_alert_threshold(struct ti_bandgap *bgp, int id,
>  {
>  	struct temp_sensor_data *ts_data = bgp->conf->sensors[id].ts_data;
>  	struct temp_sensor_registers *tsr;
> -	u32 thresh_val, reg_val, t_hot, t_cold;
> +	u32 thresh_val, reg_val, t_hot, t_cold, ctrl;
>  	int err = 0;
>  
>  	tsr = bgp->conf->sensors[id].registers;
> @@ -477,8 +477,47 @@ static int ti_bandgap_update_alert_threshold(struct ti_bandgap *bgp, int id,
>  		  ~(tsr->threshold_thot_mask | tsr->threshold_tcold_mask);
>  	reg_val |= (t_hot << __ffs(tsr->threshold_thot_mask)) |
>  		   (t_cold << __ffs(tsr->threshold_tcold_mask));
> +
> +	/**
> +	 * Errata i813:
> +	 * Spurious Thermal Alert: Talert can happen randomly while the device
> +	 * remains under the temperature limit defined for this event to trig.
> +	 * This spurious event is caused by a incorrect re-synchronization
> +	 * between clock domains. The comparison between configured threshold
> +	 * and current temperature value can happen while the value is
> +	 * transitioning (metastable), thus causing inappropriate event
> +	 * generation. No spurious event occurs as long as the threshold value
> +	 * stays unchanged. Spurious event can be generated while a thermal
> +	 * alert threshold is modified in
> +	 * CONTROL_BANDGAP_THRESHOLD_MPU/GPU/CORE/DSPEVE/IVA_n.
> +	 */
> +
> +	if (TI_BANDGAP_HAS(bgp, ERRATA_813)) {
> +		/* Mask t_hot and t_cold events at the IP Level */
> +		ctrl = ti_bandgap_readl(bgp, tsr->bgap_mask_ctrl);
> +
> +		if (hot)
> +			ctrl &= ~tsr->mask_hot_mask;
> +		else
> +			ctrl &= ~tsr->mask_cold_mask;
> +
> +		ti_bandgap_writel(bgp, ctrl, tsr->bgap_mask_ctrl);
> +	}
> +
> +	/* Write the threshold value */
>  	ti_bandgap_writel(bgp, reg_val, tsr->bgap_threshold);
>  
> +	if (TI_BANDGAP_HAS(bgp, ERRATA_813)) {
> +		/* Unmask t_hot and t_cold events at the IP Level */
> +		ctrl = ti_bandgap_readl(bgp, tsr->bgap_mask_ctrl);
> +		if (hot)
> +			ctrl |= tsr->mask_hot_mask;
> +		else
> +			ctrl |= tsr->mask_cold_mask;
> +
> +		ti_bandgap_writel(bgp, ctrl, tsr->bgap_mask_ctrl);
> +	}
> +
>  	if (err) {
>  		dev_err(bgp->dev, "failed to reprogram thot threshold\n");
>  		err = -EIO;
> diff --git a/drivers/thermal/ti-soc-thermal/ti-bandgap.h b/drivers/thermal/ti-soc-thermal/ti-bandgap.h
> index b2da3fc..0c52f7a 100644
> --- a/drivers/thermal/ti-soc-thermal/ti-bandgap.h
> +++ b/drivers/thermal/ti-soc-thermal/ti-bandgap.h
> @@ -320,7 +320,8 @@ struct ti_temp_sensor {
>   *
>   * TI_BANDGAP_FEATURE_ERRATA_814 - used to workaorund when the bandgap device
>   *	has Errata 814
> - *
> + * TI_BANDGAP_FEATURE_ERRATA_813 - used to workaorund when the bandgap device
> + *	has Errata 813
>   * 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.
>   */
> @@ -335,6 +336,7 @@ struct ti_temp_sensor {
>  #define TI_BANDGAP_FEATURE_COUNTER_DELAY	BIT(8)
>  #define TI_BANDGAP_FEATURE_HISTORY_BUFFER	BIT(9)
>  #define TI_BANDGAP_FEATURE_ERRATA_814		BIT(10)
> +#define TI_BANDGAP_FEATURE_ERRATA_813		BIT(11)
>  #define TI_BANDGAP_HAS(b, f)			\
>  			((b)->conf->features & TI_BANDGAP_FEATURE_ ## f)
>  
> -- 
> 1.9.1
> 

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