Linux-i2c Archive on lore.kernel.org
 help / color / Atom feed
From: David Laight <David.Laight@ACULAB.COM>
To: "\'Uwe Kleine-König\'" <u.kleine-koenig@pengutronix.de>
Cc: 'Christian Eggers' <ceggers@arri.de>,
	Oleksij Rempel <linux@rempel-privat.de>,
	Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	NXP Linux Team <linux-imx@nxp.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>
Subject: RE: [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag
Date: Tue, 6 Oct 2020 12:52:13 +0000
Message-ID: <0ccbfc8fe2a44796a61e59d1527fe6be@AcuMS.aculab.com> (raw)
In-Reply-To: <20201006124602.oxfyzb3atoju7sva@pengutronix.de>

From: Uwe Kleine-König
> Sent: 06 October 2020 13:46
...
> > > +static void i2c_imx_clear_irq(struct imx_i2c_struct *i2c_imx, unsigned int bits)
> > > +{
> > > +	unsigned int temp;
> > > +
> > > +	/*
> > > +	 * i2sr_clr_opcode is the value to clear all interrupts.
> > > +	 * Here we want to clear only <bits>, so we write
> > > +	 * ~i2sr_clr_opcode with just <bits> toggled.
> > > +	 */
> > > +	temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ bits;
> > > +	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
> > > +}
> >
> > That looks either wrong or maybe just overcomplicated.
> > Why isn't:
> > 	imx_i2c_write_reg(bits, i2c_imx, IMX_I2C_I2SR);
> > enough?
> 
> Your question suggests you either didn't read the comment or the comment
> is not good enough. Maybe once you understood the complication (see
> Christian's mail) you could suggest a better wording? Maybe we have to
> mention that this handles both W1C and W0C.

Yes, the comment should just say that some devices are W1C and
other W0C.
It isn't obvious from that code fragment at all.

Now for the 3rd variant which zeros the bits when they are read :-)

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)


  reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-02 15:23 [PATCH v2 0/3] i2c: imx: Fix handling of arbitration loss Christian Eggers
2020-10-02 15:23 ` [PATCH v2 1/3] i2c: imx: Fix reset of I2SR_IAL flag Christian Eggers
2020-10-05  8:05   ` Krzysztof Kozlowski
2020-10-06  6:05   ` Uwe Kleine-König
2020-10-06 10:51     ` [PATCH v3 0/3] i2c: imx: Fix handling of arbitration loss Christian Eggers
2020-10-06 10:51       ` [PATCH v3 1/3] i2c: imx: Fix reset of I2SR_IAL flag Christian Eggers
2020-10-06 12:06         ` David Laight
2020-10-06 12:30           ` Christian Eggers
2020-10-06 12:46           ` Uwe Kleine-König
2020-10-06 12:52             ` David Laight [this message]
2020-10-06 10:51       ` [PATCH v3 2/3] i2c: imx: Check for I2SR_IAL after every byte Christian Eggers
2020-10-06 10:51       ` [PATCH v3 3/3] i2c: imx: Don't generate STOP condition if arbitration has been lost Christian Eggers
2020-10-02 15:23 ` [PATCH v2 2/3] i2c: imx: Check for I2SR_IAL after every byte Christian Eggers
2020-10-05  8:07   ` Krzysztof Kozlowski
2020-10-05  9:25     ` Christian Eggers
2020-10-02 15:23 ` [PATCH v2 3/3] i2c: imx: Don't generate STOP condition if arbitration has been lost Christian Eggers
2020-10-05  8:16   ` Krzysztof Kozlowski

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=0ccbfc8fe2a44796a61e59d1527fe6be@AcuMS.aculab.com \
    --to=david.laight@aculab.com \
    --cc=ceggers@arri.de \
    --cc=festevam@gmail.com \
    --cc=kernel@pengutronix.de \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-i2c@vger.kernel.org \
    --cc=linux-imx@nxp.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@rempel-privat.de \
    --cc=s.hauer@pengutronix.de \
    --cc=shawnguo@kernel.org \
    --cc=stable@vger.kernel.org \
    --cc=u.kleine-koenig@pengutronix.de \
    /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

Linux-i2c Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-i2c/0 linux-i2c/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-i2c linux-i2c/ https://lore.kernel.org/linux-i2c \
		linux-i2c@vger.kernel.org
	public-inbox-index linux-i2c

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-i2c


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git