linux-kernel - Re: [PATCH 1/2] leds: flash: leds-qcom-flash: update torch current clamp setting

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Message-ID: <fb79df7b-1c7b-4085-9f12-35b7cd56bb87@oss.qualcomm.com>
Date: Fri, 25 Jul 2025 14:37:48 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: fenglin.wu@....qualcomm.com, kernel@....qualcomm.com,
        Lee Jones <lee@...nel.org>, Pavel Machek <pavel@...nel.org>,
        Fenglin Wu <quic_fenglinw@...cinc.com>
Cc: Subbaraman Narayanamurthy <subbaraman.narayanamurthy@....qualcomm.com>,
        linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] leds: flash: leds-qcom-flash: update torch current
 clamp setting

On 7/25/25 12:04 PM, 'Fenglin Wu via B4 Relay' via kernel wrote:
> From: Fenglin Wu <fenglin.wu@....qualcomm.com>
> 
> There is a register to clamp the flash current per LED channel when
> safety timer is disabled. It needs to be updated according to the
> maximum torch LED current setting to ensure the torch current won't
> be clamped unexpectedly.
> 
> Fixes: 96a2e242a5dc ("leds: flash: Add driver to support flash LED module in QCOM PMICs")
> Signed-off-by: Fenglin Wu <fenglin.wu@....qualcomm.com>
> ---
>  drivers/leds/flash/leds-qcom-flash.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/leds/flash/leds-qcom-flash.c b/drivers/leds/flash/leds-qcom-flash.c
> index 89cf5120f5d55bbb7e24faa8c3a946416f8fed46..9c2e41cfddcf2d50d5a633cb157084371a631d74 100644
> --- a/drivers/leds/flash/leds-qcom-flash.c
> +++ b/drivers/leds/flash/leds-qcom-flash.c
> @@ -1,6 +1,6 @@
>  // SPDX-License-Identifier: GPL-2.0-only
>  /*
> - * Copyright (c) 2022, 2024 Qualcomm Innovation Center, Inc. All rights reserved.
> + * Copyright (c) 2022, 2024-2025 Qualcomm Innovation Center, Inc. All rights reserved.
>   */
>  
>  #include <linux/bitfield.h>
> @@ -111,6 +111,7 @@ enum {
>  	REG_IRESOLUTION,
>  	REG_CHAN_STROBE,
>  	REG_CHAN_EN,
> +	REG_TORCH_CLAMP,

This is not the name of this register on at least PM8150L

>  	REG_THERM_THRSH1,
>  	REG_THERM_THRSH2,
>  	REG_THERM_THRSH3,
> @@ -127,6 +128,7 @@ static const struct reg_field mvflash_3ch_regs[REG_MAX_COUNT] = {
>  	REG_FIELD(0x47, 0, 5),                  /* iresolution	*/
>  	REG_FIELD_ID(0x49, 0, 2, 3, 1),         /* chan_strobe	*/
>  	REG_FIELD(0x4c, 0, 2),                  /* chan_en	*/
> +	REG_FIELD(0xec, 0, 6),			/* torch_clamp	*/

Please keep it sorted by address


>  	REG_FIELD(0x56, 0, 2),			/* therm_thrsh1 */
>  	REG_FIELD(0x57, 0, 2),			/* therm_thrsh2 */
>  	REG_FIELD(0x58, 0, 2),			/* therm_thrsh3 */
> @@ -142,6 +144,7 @@ static const struct reg_field mvflash_4ch_regs[REG_MAX_COUNT] = {
>  	REG_FIELD(0x49, 0, 3),			/* iresolution	*/
>  	REG_FIELD_ID(0x4a, 0, 6, 4, 1),		/* chan_strobe	*/
>  	REG_FIELD(0x4e, 0, 3),			/* chan_en	*/
> +	REG_FIELD(0xed, 0, 6),			/* torch_clamp	*/
>  	REG_FIELD(0x7a, 0, 2),			/* therm_thrsh1 */
>  	REG_FIELD(0x78, 0, 2),			/* therm_thrsh2 */
>  };
> @@ -156,6 +159,7 @@ struct qcom_flash_data {
>  	u8			max_channels;
>  	u8			chan_en_bits;
>  	u8			revision;
> +	u8			torch_clamp;
>  };
>  
>  struct qcom_flash_led {
> @@ -702,6 +706,7 @@ static int qcom_flash_register_led_device(struct device *dev,
>  	u32 current_ua, timeout_us;
>  	u32 channels[4];
>  	int i, rc, count;
> +	u8 torch_clamp;
>  
>  	count = fwnode_property_count_u32(node, "led-sources");
>  	if (count <= 0) {
> @@ -751,6 +756,12 @@ static int qcom_flash_register_led_device(struct device *dev,
>  	current_ua = min_t(u32, current_ua, TORCH_CURRENT_MAX_UA * led->chan_count);
>  	led->max_torch_current_ma = current_ua / UA_PER_MA;
>  
> +	torch_clamp = (current_ua / led->chan_count) / TORCH_IRES_UA;
> +	if (torch_clamp != 0)
> +		torch_clamp--;

In case anyone's wondering, ((1<<6) + 1) 4 * 5000 == 1280000 which we set
on some (all?) devices

Konrad