From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 953693DFC75; Mon, 4 May 2026 15:06:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777907174; cv=none; b=BVK4oTJ+FnqRhW+fdmddhZExCM87dXGf8BQyizjpMdiNEvi9G5ui1yLIFSIAIqRp7WoCzD1Azkappbo/ce8QaW49fUdJPejMr7jxTnxsZsOfXue+b2yhLAzd+nYVWZXknhOxKdvZ2lG5HlRFRAVZRGpS05ioDBLzRpgvfeHLHYI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777907174; c=relaxed/simple; bh=VGRg8Q/l5/7IklFbItHWa4BLQnJOOeYP7gWeXv6zdCU=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=TzIX9JHqr4I/Ch++YD08d5xdNX68kg2FD4iG/0iMhUcYwOkMgmL6RtfvHbkzyrmu9qcrYAJisyVe8gIEvsAdaG7QLesi4X25zm7QkM9eKnKyT4WAUF+YILLPIslp3zMWIRg7agiUyX60mLxgjzAduuDHcqBVR4O8x6jpOe/ZYS4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=guFRaS0k; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="guFRaS0k" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 57D19C2BCB8; Mon, 4 May 2026 15:06:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777907174; bh=VGRg8Q/l5/7IklFbItHWa4BLQnJOOeYP7gWeXv6zdCU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=guFRaS0kWaxDzS967TMQGvmzi0HbNvF/m+d5zuUg7j/fgibhCHU4ZMYhTA9X2NwPS WiuCoMsJgPUeGdqH6fZ/QdGN/UsNlRGYuWWoHMvk5f2AppbTPRp/v0dAv56XwjfqLk ZKjliczseYZhR7jTND36PMsJDAgq+T/S7yPccGu7NGW+YOeUvEsnnDwTOJde0pkZgB GWxCwqS+oXK6NCgyGaRVM5zcVLT6m+sAug30i3rR9tAc7Id+vfPJDKxM9A57F/m1Z6 88yQOYJPuGNu4MTL5WBz1uzRyziH33zx4w0sjKeQgeG1gL6VMOKwRD/+h/2SPJuv+p mTZ8623537tXg== Date: Mon, 4 May 2026 16:06:06 +0100 From: Jonathan Cameron To: Joshua Crofts via B4 Relay Cc: joshua.crofts1@gmail.com, David Lechner , Nuno =?UTF-8?B?U8Oh?= , Andy Shevchenko , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Andy Shevchenko Subject: Re: [PATCH v4 06/17] iio: magnetometer: ak8975: modernize polling loops with iopoll() macros Message-ID: <20260504160606.07f87f10@jic23-huawei> In-Reply-To: <20260504-magnetometer-fixes-v4-6-a291c2a7c71a@gmail.com> References: <20260504-magnetometer-fixes-v4-0-a291c2a7c71a@gmail.com> <20260504-magnetometer-fixes-v4-6-a291c2a7c71a@gmail.com> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 04 May 2026 11:48:18 +0200 Joshua Crofts via B4 Relay wrote: > From: Joshua Crofts > > The driver currently uses while loops and msleep() for polling during > conversion waits. > > Replace the custom polling loops with readx_poll_timeout() and > read_poll_timeout() macros from . This reduces > boilerplate, standardizes timeout handling and improves overall code > readability, keeping the original timing and error behaviour. Add > for USEC_PER_MSEC macro instead of using magic numbers. > > Assisted-by: Gemini:3.1-Pro > Co-developed-by: Andy Shevchenko > Signed-off-by: Andy Shevchenko > Signed-off-by: Joshua Crofts One question inline on whether it is a good idea to be paranoid about gpiod_get_value() potentially returning < 0 to indicate an error. Right now that is treated as success. > --- > drivers/iio/magnetometer/ak8975.c | 45 +++++++++++++++++---------------------- > 1 file changed, 19 insertions(+), 26 deletions(-) > > diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c > index 57f50c09cca539c3733f516a1617375e9134c349..2e750c151435da57926969a63ba9fe996d774e7a 100644 > --- a/drivers/iio/magnetometer/ak8975.c > +++ b/drivers/iio/magnetometer/ak8975.c > @@ -23,6 +23,7 @@ > #include > #include > #include > +#include > #include > #include > > @@ -652,18 +653,15 @@ static int ak8975_setup(struct i2c_client *client) > static int wait_conversion_complete_gpio(struct ak8975_data *data) > { > struct i2c_client *client = data->client; > - u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT; > int ret; > + int val; > > /* Wait for the conversion to complete. */ > - while (timeout_ms) { > - msleep(AK8975_CONVERSION_DONE_POLL_TIME); > - if (gpiod_get_value(data->eoc_gpiod)) > - break; > - timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME; > - } > - if (!timeout_ms) > - return -ETIMEDOUT; > + ret = readx_poll_timeout(gpiod_get_value, data->eoc_gpiod, val, val != 0, > + AK8975_CONVERSION_DONE_POLL_TIME * USEC_PER_MSEC, > + AK8975_MAX_CONVERSION_TIMEOUT * USEC_PER_MSEC); > + if (ret) > + return ret; Should we check val as well? It might be negative if gpiod_get_value() returned an error.. Obviously the original code didn't so this would be an improvement rather than maintaining what that was doing. > > ret = i2c_smbus_read_byte_data(client, data->def->ctrl_regs[ST1]); > if (ret < 0) > @@ -675,28 +673,23 @@ static int wait_conversion_complete_gpio(struct ak8975_data *data) > static int wait_conversion_complete_polled(struct ak8975_data *data) > { > struct i2c_client *client = data->client; > - u8 read_status; > - u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT; > int ret; > + int val; > > /* Wait for the conversion to complete. */ > - while (timeout_ms) { > - msleep(AK8975_CONVERSION_DONE_POLL_TIME); > - ret = i2c_smbus_read_byte_data(client, > - data->def->ctrl_regs[ST1]); > - if (ret < 0) { > - dev_err(&client->dev, "Error in reading ST1\n"); > - return ret; > - } > - read_status = ret; > - if (read_status) > - break; > - timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME; > + ret = read_poll_timeout(i2c_smbus_read_byte_data, val, val != 0, > + AK8975_CONVERSION_DONE_POLL_TIME * USEC_PER_MSEC, > + AK8975_MAX_CONVERSION_TIMEOUT * USEC_PER_MSEC, > + true, > + client, data->def->ctrl_regs[ST1]); > + if (ret) > + return ret; > + if (val < 0) { > + dev_err(&client->dev, "Error in reading ST1\n"); > + return val; > } > - if (!timeout_ms) > - return -ETIMEDOUT; > > - return read_status; > + return val; > } > > /* Returns 0 if the end of conversion interrupt occurred or -ETIMEDOUT otherwise */ >