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Message-Id: <20240509-qcom_flash_thermal_derating-v1-1-1d5e68e5d71c@quicinc.com>
Date: Thu, 09 May 2024 10:07:23 +0800
From: Fenglin Wu via B4 Relay <devnull+quic_fenglinw.quicinc.com@...nel.org>
To: kernel@...cinc.com, Pavel Machek <pavel@....cz>,
Lee Jones <lee@...nel.org>
Cc: linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
David Collins <quic_collinsd@...cinc.com>,
Subbaraman Narayanamurthy <quic_subbaram@...cinc.com>,
Fenglin Wu <quic_fenglinw@...cinc.com>
Subject: [PATCH] leds: flash: leds-qcom-flash: limit LED current based on
thermal condition
From: Fenglin Wu <quic_fenglinw@...cinc.com>
The flash module has status bits to indicate different thermal
conditions which are called as OTSTx. For each OTSTx status,
there is a recommended total flash current for all channels to
prevent the flash module entering into higher thermal level.
For example, the total flash current should be limited to 1000mA/500mA
respectively when the HW reaches the OTST1/OTST2 thermal level.
Signed-off-by: Fenglin Wu <quic_fenglinw@...cinc.com>
---
drivers/leds/flash/leds-qcom-flash.c | 151 ++++++++++++++++++++++++++++++++++-
1 file changed, 150 insertions(+), 1 deletion(-)
diff --git a/drivers/leds/flash/leds-qcom-flash.c b/drivers/leds/flash/leds-qcom-flash.c
index 7c99a3039171..036c9e3cf974 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 Qualcomm Innovation Center, Inc. All rights reserved.
+ * Copyright (c) 2022, 2024 Qualcomm Innovation Center, Inc. All rights reserved.
*/
#include <linux/bitfield.h>
@@ -14,6 +14,9 @@
#include <media/v4l2-flash-led-class.h>
/* registers definitions */
+#define FLASH_REVISION_REG 0x00
+#define FLASH_4CH_REVISION_V0P1 0x01
+
#define FLASH_TYPE_REG 0x04
#define FLASH_TYPE_VAL 0x18
@@ -73,6 +76,16 @@
#define UA_PER_MA 1000
+/* thermal threshold constants */
+#define OTST_3CH_MIN_VAL 3
+#define OTST1_4CH_MIN_VAL 0
+#define OTST1_4CH_MIN_VAL_V0P1 3
+#define OTST2_4CH_MIN_VAL 0
+
+#define OTST1_MAX_CURRENT_MA 1000
+#define OTST2_MAX_CURRENT_MA 500
+#define OTST3_MAX_CURRENT_MA 200
+
enum hw_type {
QCOM_MVFLASH_3CH,
QCOM_MVFLASH_4CH,
@@ -98,6 +111,7 @@ enum {
REG_IRESOLUTION,
REG_CHAN_STROBE,
REG_CHAN_EN,
+ REG_THERM_THRSH,
REG_MAX_COUNT,
};
@@ -111,6 +125,7 @@ static 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_ID(0x56, 0, 2, 3, 1), /* therm_thrsh */
};
static struct reg_field mvflash_4ch_regs[REG_MAX_COUNT] = {
@@ -123,6 +138,7 @@ static 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_ID(0x7a, 0, 2, 2, 1), /* therm_thrsh */
};
struct qcom_flash_data {
@@ -130,9 +146,11 @@ struct qcom_flash_data {
struct regmap_field *r_fields[REG_MAX_COUNT];
struct mutex lock;
enum hw_type hw_type;
+ u32 total_ma;
u8 leds_count;
u8 max_channels;
u8 chan_en_bits;
+ u8 revision;
};
struct qcom_flash_led {
@@ -143,6 +161,7 @@ struct qcom_flash_led {
u32 max_timeout_ms;
u32 flash_current_ma;
u32 flash_timeout_ms;
+ u32 current_in_use_ma;
u8 *chan_id;
u8 chan_count;
bool enabled;
@@ -172,6 +191,121 @@ static int set_flash_module_en(struct qcom_flash_led *led, bool en)
return rc;
}
+static int update_allowed_flash_current(struct qcom_flash_led *led, u32 *current_ma, bool strobe)
+{
+ struct qcom_flash_data *flash_data = led->flash_data;
+ u32 therm_ma, avail_ma, thrsh[3], min_thrsh, sts;
+ int rc;
+
+ mutex_lock(&flash_data->lock);
+ /*
+ * Put previously allocated current into allowed budget in either of these two cases:
+ * 1) LED is disabled;
+ * 2) LED is enabled repeatedly
+ */
+ if (!strobe || (strobe && led->current_in_use_ma != 0)) {
+ if (flash_data->total_ma >= led->current_in_use_ma)
+ flash_data->total_ma -= led->current_in_use_ma;
+ else
+ flash_data->total_ma = 0;
+
+ led->current_in_use_ma = 0;
+ if (!strobe) {
+ mutex_unlock(&flash_data->lock);
+ return 0;
+ }
+ }
+
+ /*
+ * Cache the default thermal threshold settings, and set them to the lowest levels before
+ * reading over-temp real time status. If over-temp has been triggered at the lowest
+ * threshold, it's very likely that it would be triggered at a higher (default) threshold
+ * when more flash current is requested. Prevent device from triggering over-temp condition
+ * by limiting the flash current for the new request.
+ */
+ rc = regmap_fields_read(flash_data->r_fields[REG_THERM_THRSH], 0, &thrsh[0]);
+ if (rc < 0)
+ goto unlock;
+
+ rc = regmap_fields_read(flash_data->r_fields[REG_THERM_THRSH], 1, &thrsh[1]);
+ if (rc < 0)
+ goto unlock;
+
+ if (flash_data->hw_type == QCOM_MVFLASH_3CH) {
+ rc = regmap_fields_read(flash_data->r_fields[REG_THERM_THRSH], 2, &thrsh[2]);
+ if (rc < 0)
+ goto unlock;
+ }
+
+ min_thrsh = OTST_3CH_MIN_VAL;
+ if (flash_data->hw_type == QCOM_MVFLASH_4CH)
+ min_thrsh = (flash_data->revision == FLASH_4CH_REVISION_V0P1) ?
+ OTST1_4CH_MIN_VAL_V0P1 : OTST1_4CH_MIN_VAL;
+ rc = regmap_fields_write(flash_data->r_fields[REG_THERM_THRSH], 0, min_thrsh);
+ if (rc < 0)
+ goto unlock;
+
+ if (flash_data->hw_type == QCOM_MVFLASH_4CH)
+ min_thrsh = OTST2_4CH_MIN_VAL;
+ rc = regmap_fields_write(flash_data->r_fields[REG_THERM_THRSH], 1, min_thrsh);
+ if (rc < 0)
+ goto restore;
+
+ if (flash_data->hw_type == QCOM_MVFLASH_3CH) {
+ rc = regmap_fields_write(flash_data->r_fields[REG_THERM_THRSH], 2, min_thrsh);
+ if (rc < 0)
+ goto restore;
+ }
+
+ /* read thermal level status to get corresponding derating flash current */
+ rc = regmap_field_read(flash_data->r_fields[REG_STATUS2], &sts);
+ if (rc)
+ goto restore;
+
+ therm_ma = FLASH_TOTAL_CURRENT_MAX_UA / 1000;
+ if (flash_data->hw_type == QCOM_MVFLASH_3CH) {
+ if (sts & FLASH_STS_3CH_OTST3)
+ therm_ma = OTST3_MAX_CURRENT_MA;
+ else if (sts & FLASH_STS_3CH_OTST2)
+ therm_ma = OTST2_MAX_CURRENT_MA;
+ else if (sts & FLASH_STS_3CH_OTST1)
+ therm_ma = OTST1_MAX_CURRENT_MA;
+ } else {
+ if (sts & FLASH_STS_4CH_OTST2)
+ therm_ma = OTST2_MAX_CURRENT_MA;
+ else if (sts & FLASH_STS_4CH_OTST1)
+ therm_ma = OTST1_MAX_CURRENT_MA;
+ }
+
+ /* calculate the allowed flash current for the request */
+ if (therm_ma <= flash_data->total_ma)
+ avail_ma = 0;
+ else
+ avail_ma = therm_ma - flash_data->total_ma;
+ *current_ma = min_t(u32, *current_ma, avail_ma);
+ led->current_in_use_ma = *current_ma;
+ flash_data->total_ma += led->current_in_use_ma;
+
+ dev_dbg(led->flash.led_cdev.dev, "allowed flash current: %dmA, total current: %dmA\n",
+ led->current_in_use_ma, flash_data->total_ma);
+restore:
+ /* Restore to default thermal threshold settings */
+ rc = regmap_fields_write(flash_data->r_fields[REG_THERM_THRSH], 0, thrsh[0]);
+ if (rc < 0)
+ goto unlock;
+
+ rc = regmap_fields_write(flash_data->r_fields[REG_THERM_THRSH], 1, thrsh[1]);
+ if (rc < 0)
+ goto unlock;
+
+ if (flash_data->hw_type == QCOM_MVFLASH_3CH)
+ rc = regmap_fields_write(flash_data->r_fields[REG_THERM_THRSH], 2, thrsh[2]);
+
+unlock:
+ mutex_unlock(&flash_data->lock);
+ return rc;
+}
+
static int set_flash_current(struct qcom_flash_led *led, u32 current_ma, enum led_mode mode)
{
struct qcom_flash_data *flash_data = led->flash_data;
@@ -313,6 +447,10 @@ static int qcom_flash_strobe_set(struct led_classdev_flash *fled_cdev, bool stat
if (rc)
return rc;
+ rc = update_allowed_flash_current(led, &led->flash_current_ma, state);
+ if (rc < 0)
+ return rc;
+
rc = set_flash_current(led, led->flash_current_ma, FLASH_MODE);
if (rc)
return rc;
@@ -429,6 +567,10 @@ static int qcom_flash_led_brightness_set(struct led_classdev *led_cdev,
if (rc)
return rc;
+ rc = update_allowed_flash_current(led, ¤t_ma, enable);
+ if (rc < 0)
+ return rc;
+
rc = set_flash_current(led, current_ma, TORCH_MODE);
if (rc)
return rc;
@@ -703,6 +845,13 @@ static int qcom_flash_led_probe(struct platform_device *pdev)
flash_data->hw_type = QCOM_MVFLASH_4CH;
flash_data->max_channels = 4;
regs = mvflash_4ch_regs;
+ rc = regmap_read(regmap, reg_base + FLASH_REVISION_REG, &val);
+ if (rc < 0) {
+ dev_err(dev, "Read flash LED module revision failed, rc=%d\n", rc);
+ return rc;
+ }
+
+ flash_data->revision = val;
} else {
dev_err(dev, "flash LED subtype %#x is not yet supported\n", val);
return -ENODEV;
---
base-commit: ca66b10a11da3c445c9c0ca1184f549bbe9061f2
change-id: 20240507-qcom_flash_thermal_derating-260b1f3c757c
Best regards,
--
Fenglin Wu <quic_fenglinw@...cinc.com>
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