{"id":2223883,"url":"http://patchwork.ozlabs.org/api/patches/2223883/?format=json","web_url":"http://patchwork.ozlabs.org/project/rtc-linux/patch/20260416095706.3212158-3-adriana@arista.com/","project":{"id":9,"url":"http://patchwork.ozlabs.org/api/projects/9/?format=json","name":"Linux RTC development","link_name":"rtc-linux","list_id":"linux-rtc.vger.kernel.org","list_email":"linux-rtc@vger.kernel.org","web_url":"","scm_url":"","webscm_url":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260416095706.3212158-3-adriana@arista.com>","list_archive_url":null,"date":"2026-04-16T09:57:06","name":"[v2,2/2] rtc: bq32000: add configurable delay between RTC reads","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"d4bf128ccd1e372298537a2a60c1edbd6852c8f5","submitter":{"id":91944,"url":"http://patchwork.ozlabs.org/api/people/91944/?format=json","name":"Adriana Stancu","email":"adriana@arista.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/rtc-linux/patch/20260416095706.3212158-3-adriana@arista.com/mbox/","series":[{"id":500129,"url":"http://patchwork.ozlabs.org/api/series/500129/?format=json","web_url":"http://patchwork.ozlabs.org/project/rtc-linux/list/?series=500129","date":"2026-04-16T09:57:04","name":"rtc: bq32000: Add settle delay for aggressive polling","version":2,"mbox":"http://patchwork.ozlabs.org/series/500129/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2223883/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2223883/checks/","tags":{},"related":[],"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-rtc@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=arista.com header.i=@arista.com header.a=rsa-sha256\n header.s=google header.b=A7xhCwCP;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c04:e001:36c::12fc:5321; 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This results in stale data reads or select() timeouts\nin userspace.\n\nThis patch introduces a configurable settle delay via \"ti,read-settle-us\"\nproperty. If this property is specified, the driver uses a delay before\nreading the RTC registers. This provides a sufficient idle time for the\nhardware to sync with the register buffer.\n\nSigned-off-by: Adriana Stancu \n---\n drivers/rtc/rtc-bq32k.c | 34 ++++++++++++++++++++++++++++------\n 1 file changed, 28 insertions(+), 6 deletions(-)","diff":"diff --git a/drivers/rtc/rtc-bq32k.c b/drivers/rtc/rtc-bq32k.c\nindex 7ad34539be4d..0cbfa0909732 100644\n--- a/drivers/rtc/rtc-bq32k.c\n+++ b/drivers/rtc/rtc-bq32k.c\n@@ -16,6 +16,7 @@\n #include \n #include \n #include \n+#include \n \n #define BQ32K_SECONDS\t\t0x00\t/* Seconds register address */\n #define BQ32K_SECONDS_MASK\t0x7F\t/* Mask over seconds value */\n@@ -48,6 +49,11 @@ struct bq32k_regs {\n \tuint8_t\t\tyears;\n };\n \n+struct bq32k_data {\n+\tstruct rtc_device *rtc;\n+\tu32 read_delay_us;\n+};\n+\n static struct i2c_driver bq32k_driver;\n \n static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len)\n@@ -89,9 +95,17 @@ static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len)\n \n static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm)\n {\n+\tstruct bq32k_data *bq32k = dev_get_drvdata(dev);\n \tstruct bq32k_regs regs;\n \tint error;\n \n+\t/*\n+\t * When the device doesn't have the interrupt connected, prevent\n+\t * userpace from polling the RTC registers to frequently.\n+\t */\n+\tif (bq32k && bq32k->read_delay_us)\n+\t\tusleep_range(bq32k->read_delay_us, bq32k->read_delay_us + 50);\n+\n \terror = bq32k_read(dev, ®s, 0, sizeof(regs));\n \tif (error)\n \t\treturn error;\n@@ -253,13 +267,18 @@ static void bq32k_sysfs_unregister(struct device *dev)\n static int bq32k_probe(struct i2c_client *client)\n {\n \tstruct device *dev = &client->dev;\n-\tstruct rtc_device *rtc;\n+\tstruct bq32k_data *bq32k;\n \tuint8_t reg;\n \tint error;\n+\tuint32_t settle_us = 0;\n \n \tif (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))\n \t\treturn -ENODEV;\n \n+\tbq32k = devm_kzalloc(dev, sizeof(*bq32k), GFP_KERNEL);\n+\tif (!bq32k)\n+\t\treturn -ENOMEM;\n+\n \t/* Check Oscillator Stop flag */\n \terror = bq32k_read(dev, ®, BQ32K_SECONDS, 1);\n \tif (!error && (reg & BQ32K_STOP)) {\n@@ -280,10 +299,13 @@ static int bq32k_probe(struct i2c_client *client)\n \tif (client->dev.of_node)\n \t\ttrickle_charger_of_init(dev, client->dev.of_node);\n \n-\trtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name,\n-\t\t\t\t\t\t&bq32k_rtc_ops, THIS_MODULE);\n-\tif (IS_ERR(rtc))\n-\t\treturn PTR_ERR(rtc);\n+\tbq32k->rtc = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name,\n+\t\t\t\t\t &bq32k_rtc_ops, THIS_MODULE);\n+\tif (IS_ERR(bq32k->rtc))\n+\t\treturn PTR_ERR(bq32k->rtc);\n+\n+\tdevice_property_read_u32(dev, \"ti,read-settle-us\", &settle_us);\n+\tbq32k->read_delay_us = settle_us;\n \n \terror = bq32k_sysfs_register(&client->dev);\n \tif (error) {\n@@ -293,7 +315,7 @@ static int bq32k_probe(struct i2c_client *client)\n \t}\n \n \n-\ti2c_set_clientdata(client, rtc);\n+\ti2c_set_clientdata(client, bq32k);\n \n \treturn 0;\n }\n","prefixes":["v2","2/2"]}