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[2001:1c00:c32:7800:5bfa:a036:83f0:f9ec]) by smtp.gmail.com with ESMTPSA id k22-20020a1709063fd600b00862497eafb2sm8408915ejj.103.2023.01.18.02.52.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 18 Jan 2023 02:52:48 -0800 (PST) Message-ID: Date: Wed, 18 Jan 2023 11:52:48 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH] iio: light: cm32181: Fix PM support on system with 2 I2C resources To: Kai-Heng Feng Cc: ktsai@capellamicro.com, jic23@kernel.org, lars@metafoo.de, Wahaj , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org References: <20230117160951.282581-1-kai.heng.feng@canonical.com> <5c95d25b-ff26-053b-efc8-5f6fd979c7e2@redhat.com> Content-Language: en-US, nl From: Hans de Goede In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org Hi, On 1/18/23 06:15, Kai-Heng Feng wrote: > On Wed, Jan 18, 2023 at 11:29 AM Kai-Heng Feng > wrote: >> >> Hi Hans, >> >> On Wed, Jan 18, 2023 at 1:21 AM Hans de Goede wrote: >>> >>> Hi, >>> >>> On 1/17/23 17:09, Kai-Heng Feng wrote: >>>> Commit c1e62062ff54 ("iio: light: cm32181: Handle CM3218 ACPI devices >>>> with 2 I2C resources") creates a second client for the actual I2C >>>> address, but the "struct device" passed to PM ops is the first client >>>> that can't talk to the sensor. >>>> >>>> That means the I2C transfers in both suspend and resume routines can >>>> fail and blocking the whole suspend process. >>>> >>>> Instead of using the first client for I2C transfer, store the cm32181 >>>> private struct on both cases so the PM ops can get the correct I2C >>>> client to perfrom suspend and resume. >>>> >>>> Fixes: 68c1b3dd5c48 ("iio: light: cm32181: Add PM support") >>>> Tested-by: Wahaj >>>> Signed-off-by: Kai-Heng Feng >>> >>> Thank you for this fix. I had looking into this on my todo list, >>> since I have been seeing some bug reports about this too. >>> >>> One remark inline: >>> >>>> --- >>>> drivers/iio/light/cm32181.c | 11 +++++++---- >>>> 1 file changed, 7 insertions(+), 4 deletions(-) >>>> >>>> diff --git a/drivers/iio/light/cm32181.c b/drivers/iio/light/cm32181.c >>>> index 001055d097509..0f319c891353c 100644 >>>> --- a/drivers/iio/light/cm32181.c >>>> +++ b/drivers/iio/light/cm32181.c >>>> @@ -440,6 +440,8 @@ static int cm32181_probe(struct i2c_client *client) >>>> if (!indio_dev) >>>> return -ENOMEM; >>>> >>>> + i2c_set_clientdata(client, indio_dev); >>>> + >>> >>> Why move this up, the suspend/resume callbacks cannot run until >>> probe() completes, so no need for this change. >> >> The intention is to save indio_dev as drvdata in the first (i.e. >> original) i2c_client's dev. >> >>> >>>> /* >>>> * Some ACPI systems list 2 I2C resources for the CM3218 sensor, the >>>> * SMBus Alert Response Address (ARA, 0x0c) and the actual I2C address. >>>> @@ -458,9 +460,9 @@ static int cm32181_probe(struct i2c_client *client) >>>> client = i2c_acpi_new_device(dev, 1, &board_info); >>>> if (IS_ERR(client)) >>>> return PTR_ERR(client); >>>> - } >>>> >>>> - i2c_set_clientdata(client, indio_dev); >>>> + i2c_set_clientdata(client, indio_dev); >>>> + } >>> >>> And moving it inside the if block here (instead of just dropping it) >>> is also weird. I guess you meant to just delete it since you moved it up. >> >> Doesn't i2c_acpi_new_device() creates a new i2c_client (and its dev embedded)? >> >> So the intention is to save indio_dev for the second (ARA case) i2c_client too. >> >>> >>>> >>>> cm32181 = iio_priv(indio_dev); >>>> cm32181->client = client; >>> >>> Also note that the ->client used in suspend/resume now is not set until >>> here, so moving the i2c_set_clientdata() up really does not do anything. >>> >>> I beleive it would be best to just these 2 hunks from the patch and >>> only keep the changes to the suspend/resume callbacks. >> >> Yes, it seems like those 2 hunks are not necessary. Let me send a new patch. > > if (ACPI_HANDLE(dev) && client->addr == SMBUS_ALERT_RESPONSE_ADDRESS) { > ... > client = i2c_acpi_new_device(dev, 1, &board_info); > ... > } > i2c_set_clientdata(client, indio_dev); > > It means the indio_dev is only assigned to the new i2c_client->dev's > drvdata, the original dev's drvdata remains NULL. > So we need to assign it before the original client gets replaced by > the new one, otherwise we can't get cm32181 in PM ops. You are right, my bad. The original code has a bug where it indeed was making the i2c_set_clientdata() call on the wrong client device. So the i2c_set_clientdata() call needs to be moved up. There is no need to also call i2c_set_clientdata() on the dummy i2c-client though. That one does not have a driver attached. The suspend/resume callbacks are made on the original client-dev, not on the one of the dummy-client (which is the one which we actually use to communicate). >> But I do wonder what happens for the removing case? Will the second >> i2c_client leak? Yes it does, good point. That should probably also be fixed, but that needs to be a different / second patch. Regards, Hans >>>> @@ -490,7 +492,8 @@ static int cm32181_probe(struct i2c_client *client) >>>> >>>> static int cm32181_suspend(struct device *dev) >>>> { >>>> - struct i2c_client *client = to_i2c_client(dev); >>>> + struct cm32181_chip *cm32181 = iio_priv(dev_get_drvdata(dev)); >>>> + struct i2c_client *client = cm32181->client; >>>> >>>> return i2c_smbus_write_word_data(client, CM32181_REG_ADDR_CMD, >>>> CM32181_CMD_ALS_DISABLE); >>>> @@ -498,8 +501,8 @@ static int cm32181_suspend(struct device *dev) >>>> >>>> static int cm32181_resume(struct device *dev) >>>> { >>>> - struct i2c_client *client = to_i2c_client(dev); >>>> struct cm32181_chip *cm32181 = iio_priv(dev_get_drvdata(dev)); >>>> + struct i2c_client *client = cm32181->client; >>>> >>>> return i2c_smbus_write_word_data(client, CM32181_REG_ADDR_CMD, >>>> cm32181->conf_regs[CM32181_REG_ADDR_CMD]); >>> >