linux-kernel - [PATCH v3 3/3] misc: eeprom: at24: register nvmem only after eeprom is ready to use

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Message-Id: <20200831015539.26811-4-vadym.kochan@plvision.eu>
Date:   Mon, 31 Aug 2020 04:55:39 +0300
From:   Vadym Kochan <vadym.kochan@...ision.eu>
To:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Vadym Kochan <vadym.kochan@...ision.eu>
Subject: [PATCH v3 3/3] misc: eeprom: at24: register nvmem only after eeprom is ready to use

During nvmem_register() the nvmem core sends notifications when:

    - cell added
    - nvmem added

and during these notifications some callback func may access the nvmem
device, which will fail in case of at24 eeprom because regulator and pm
are enabled after nvmem_register().

Signed-off-by: Vadym Kochan <vadym.kochan@...ision.eu>
---
v3:
    1) at24 driver enables regulator and pm state machine after nvmem
       registration which does not allow to use it on handing NVMEM_PRE_ADD event.

 drivers/misc/eeprom/at24.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 2591c21b2b5d..26a23abc053d 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -692,10 +692,6 @@ static int at24_probe(struct i2c_client *client)
 	nvmem_config.word_size = 1;
 	nvmem_config.size = byte_len;
 
-	at24->nvmem = devm_nvmem_register(dev, &nvmem_config);
-	if (IS_ERR(at24->nvmem))
-		return PTR_ERR(at24->nvmem);
-
 	i2c_set_clientdata(client, at24);
 
 	err = regulator_enable(at24->vcc_reg);
@@ -708,6 +704,13 @@ static int at24_probe(struct i2c_client *client)
 	pm_runtime_set_active(dev);
 	pm_runtime_enable(dev);
 
+	at24->nvmem = devm_nvmem_register(dev, &nvmem_config);
+	if (IS_ERR(at24->nvmem)) {
+		pm_runtime_disable(dev);
+		regulator_disable(at24->vcc_reg);
+		return PTR_ERR(at24->nvmem);
+	}
+
 	/*
 	 * Perform a one-byte test read to verify that the
 	 * chip is functional.
-- 
2.17.1