From: Wolfram Sang <wsa@the-dreams.de>
To: Sebastian Reichel <sre@kernel.org>
Cc: Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-i2c@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCHv2] i2c: add sc18is600 driver
Date: Sat, 29 Jul 2017 14:03:38 +0200 [thread overview]
Message-ID: <20170729120338.5suksarziutwa4o3@ninjato> (raw)
In-Reply-To: <20170701150831.20197-1-sre@kernel.org>
[-- Attachment #1: Type: text/plain, Size: 3137 bytes --]
Hi,
thanks for V2.
On Sat, Jul 01, 2017 at 05:08:31PM +0200, Sebastian Reichel wrote:
> This adds an I²C master driver for SPI -> I²C bus bridge chips.
> It currently supports NXP's SC18IS600 and SC18IS601, as well as
> Silicon Labs' CP2120. The driver was only tested on SC18IS600.
I prefer 'I2C' to "I²C' to keep things simple, but I'll leave it to you.
> +++ b/Documentation/devicetree/bindings/i2c/i2c-cp2120.txt
> @@ -0,0 +1 @@
> +Please see binding for i2c-sc18is600
I still prefer this to be dropped. There is no i2c-cp2120 driver.
> + * Datasheets:
> + * - http://www.nxp.com/documents/data_sheet/SC18IS600.pdf
> + * - https://www.silabs.com/documents/public/data-sheets/CP2120.pdf
Nice pointers.
> +static int sc18is600_read_write(struct sc18is600dev *s600dev,
This function used to be named '*_read_after_write' which is correct.
'*_read_write' sounds like it does the opposite!
> +static int sc18is600_xfer(struct i2c_adapter *adapter,
> + struct i2c_msg *msgs, int num)
> +{
> + struct sc18is600dev *s600dev = adapter->algo_data;
> + int read_operations = 0;
> + bool ignore_nak = false;
> + int i, err;
> +
> + for (i = 0; i < num; i++) {
> + if (msgs[i].len > s600dev->chip->buffer_size)
> + return -EOPNOTSUPP;
> +
> + /* chip only support standard read & write */
> + if (msgs[i].flags & ~I2C_M_RD)
> + return -EOPNOTSUPP;
This will bail out on I2C_M_IGNORE_NAK which you added support for.
Didn't you test that?
> +
> + if (msgs[i].flags & I2C_M_RD)
> + read_operations++;
> + }
I'd think the for loop can completely go by populating an i2c_quirks
structure. From what I see, you'd need I2C_AQ_COMB |
I2C_AQ_COMB_WRITE_FIRST with max_comb_1st_msg_len and
max_comb_2nd_msg_len properly set. But please double check.
> +
> + reinit_completion(&s600dev->completion);
> +
> + if (num == 1) {
> + if (msgs[0].flags & I2C_M_IGNORE_NAK)
> + ignore_nak = true;
Why do you ignore NAK only for 1 message?
> +
> + if (read_operations == 1)
> + err = sc18is600_read(s600dev, &msgs[0]);
> + else
> + err = sc18is600_write(s600dev, &msgs[0]);
> + } else if (num == 2) {
> + if (read_operations == 1)
> + err = sc18is600_read_write(s600dev, &msgs[0], &msgs[1]);
> + else
> + err = sc18is600_write_write(s600dev, &msgs[0], &msgs[1]);
> + } else {
> + return -EOPNOTSUPP;
> + }
With i2c_quirks, the last else-block could also go.
> + if (!err) {
> + dev_warn(&s600dev->spi->dev,
> + "timeout waiting for irq, poll status register");
Don't log on timeouts, it is not unusual to happen on the bus.
> + s600dev->state = SC18IS600_STAT_BUSY;
> + regmap_read(s600dev->regmap, SC18IS600_REG_I2C_STAT,
> + &s600dev->state);
> + }
...
> + s600dev->spi = spi;
> + s600dev->adapter.owner = THIS_MODULE;
> + s600dev->adapter.class = I2C_CLASS_DEPRECATED;
Huh? This is a new driver, why do you need it? Hmm, maybe I could
rephrase the docs a little.
...
> + err = clk_prepare_enable(s600dev->clk);
You never disable the clock anywhere.
Regards,
Wolfram
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
prev parent reply other threads:[~2017-07-29 12:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-01 15:08 [PATCHv2] i2c: add sc18is600 driver Sebastian Reichel
2017-07-29 12:03 ` Wolfram Sang [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170729120338.5suksarziutwa4o3@ninjato \
--to=wsa@the-dreams.de \
--cc=devicetree@vger.kernel.org \
--cc=linux-i2c@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=robh+dt@kernel.org \
--cc=sre@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).