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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <353b1b08-a57a-4f29-abc5-8d6e36b3190b@oss.qualcomm.com>
Date: Fri, 25 Jul 2025 14:45:36 +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 2:37 PM, Konrad Dybcio wrote:
> 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

Scratch "the + 1", I had both the width of the field and its max
value in mind.. the rhs still matches..

Konrad