linux-kernel - Re: [PATCH v2 2/2] i2c: New bus driver for the QUP I2C controller

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Date:	Thu, 16 Jan 2014 15:37:24 +0200
From:	"Ivan T. Ivanov" <iivanov@...sol.com>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	Bjorn Andersson <bjorn.andersson@...ymobile.com>,
	Rob Herring <rob.herring@...xeda.com>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Rob Landley <rob@...dley.net>,
	Wolfram Sang <wsa@...-dreams.de>,
	Grant Likely <grant.likely@...aro.org>,
	Jean Delvare <khali@...ux-fr.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	James Ralston <james.d.ralston@...el.com>,
	Bill Brown <bill.e.brown@...el.com>,
	Matt Porter <matt.porter@...aro.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 2/2] i2c: New bus driver for the QUP I2C controller


Hi,

On Wed, 2014-01-15 at 08:46 -0800, Stephen Boyd wrote: 
> On 01/13, Bjorn Andersson wrote:
> > +/*
> > + * QUP driver for Qualcomm MSM platforms
> > + *
> > + */
> 
> This comment seems redundant, we know what file we're looking at.
> 
> > +
> > +struct qup_i2c_dev {
> > +	struct device		*dev;
> > +	void __iomem		*base;
> > +	struct pinctrl		*pctrl;
> 
> This is unused.
> 
> > +	int			irq;
> > +	struct clk		*clk;
> > +	struct clk		*pclk;
> > +	struct i2c_adapter	adap;
> > +
> > +	int			clk_freq;
> 
> This is only ever used in probe, so why do we need to store it
> away?
> 
> > +	int			clk_ctl;
> > +	int			one_bit_t;
> > +	int			out_fifo_sz;
> > +	int			in_fifo_sz;
> > +	int			out_blk_sz;
> > +	int			in_blk_sz;
> > +	unsigned long		xfer_time;
> > +	unsigned long		wait_idle;
> > +
> > +	struct i2c_msg		*msg;
> > +	/* Current possion in user message buffer */
> 
> s/possion/position/?
> 
> > +	int			pos;
> > +	/* Keep number of bytes left to be transmitted */
> > +	int			cnt;
> > +	/* I2C protocol errors */
> > +	u32			bus_err;
> > +	/* QUP core errors */
> > +	u32			qup_err;
> > +	/*
> > +	 * maximum bytes that could be send (per iterration). could be
> 
> s/iterration/iteration/?
> 
> > +	 * equal of fifo size or block size (in block mode)
> > +	 */
> > +	int			chunk_sz;
> > +	struct completion	xfer;
> > +};
> > +
> > +static irqreturn_t qup_i2c_interrupt(int irq, void *dev)
> > +{
> > +	struct qup_i2c_dev *qup = dev;
> > +	u32 bus_err;
> > +	u32 qup_err;
> > +	u32 opflags;
> > +
> [...]
> > +
> > +	if (opflags & QUP_OUT_SVC_FLAG)
> > +		writel(QUP_OUT_SVC_FLAG, qup->base + QUP_OPERATIONAL);
> > +
> > +	if (!(qup->msg->flags == I2C_M_RD))
> 
> Should this be?
> 
> 	if (!(qup->msg->flags & I2C_M_RD))
> 
> Otherwise it should be
> 
> 	if (qup->msg->flags != I2C_M_RD)
> 

This check is actually broken. Intention was that if this is read
transaction and there is no QUP_MX_INPUT_DONE or QUP_IN_SVC_FLAG
to exit without wakeup transfer thread. As is it now it will never
complete write transactions.

Regards,
Ivan

> > +		return IRQ_HANDLED;
> > +
> > +	if ((opflags & QUP_MX_INPUT_DONE) || (opflags & QUP_IN_SVC_FLAG))
> > +		writel(QUP_IN_SVC_FLAG, qup->base + QUP_OPERATIONAL);
> > +
> > +done:
> > +	qup->qup_err = qup_err;
> > +	qup->bus_err = bus_err;
> > +	complete(&qup->xfer);
> > +	return IRQ_HANDLED;
> > +}
> > +


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