linux-kernel - Re: [PATCH v3 1/7] mfd: add pruss mfd driver.

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Date:	Wed, 30 Mar 2011 12:46:07 +0530
From:	"Subhasish Ghosh" <subhasish@...tralsolutions.com>
To:	"Arnd Bergmann" <arnd@...db.de>,
	<linux-arm-kernel@...ts.infradead.org>
Cc:	<davinci-linux-open-source@...ux.davincidsp.com>,
	<sachi@...tralsolutions.com>,
	"Samuel Ortiz" <sameo@...ux.intel.com>, <nsekhar@...com>,
	"open list" <linux-kernel@...r.kernel.org>, <m-watkins@...com>,
	"Marc Kleine-Budde" <mkl@...gutronix.de>,
	"Stalin Srinivasan" <stalin.s@...tralsolutions.com>
Subject: Re: [PATCH v3 1/7] mfd: add pruss mfd driver.


>> +s32 pruss_disable(struct device *dev, u8 pruss_num)
>> +{
>> + struct da8xx_pruss *pruss = dev_get_drvdata(dev->parent);
>> + struct da8xx_prusscore_regs *h_pruss;
>> + struct pruss_map *pruss_mmap = (struct pruss_map *)pruss->ioaddr;
>> + u32 temp_reg;
>> + u32 delay_cnt;
>
> Can you explain the significance of pruss_num? As far as I
> can tell, you always pass constants in here, so it should
> be possible to determine the number from the device.

SG - The number is not programmed in the device, I need something to decide 
which PRU to disable
or enable.

>> + ~DA8XX_PRUCORE_CONTROL_COUNTENABLE_MASK) |
>> + ((DA8XX_PRUCORE_CONTROL_COUNTENABLE_DISABLE <<
>> + DA8XX_PRUCORE_CONTROL_COUNTENABLE_SHIFT) &
>> + DA8XX_PRUCORE_CONTROL_COUNTENABLE_MASK);
>> + __raw_writel(temp_reg, &h_pruss->CONTROL);
>
> Better use readl/writel, the __raw_ variants are not reliable in general.

SG - Have changed this to iowrite32 and variants.


>> +
>> + /* Reset PRU0 */
>> + for (delay_cnt = 0x10000; delay_cnt > 0; delay_cnt--)
>> + __raw_writel(DA8XX_PRUCORE_CONTROL_RESETVAL,
>> + &h_pruss->CONTROL);
>
> Why do you need to reset it 65536 times? Is once not enough?

SG - I am not sure why this was done, but I have removed it now.

>> + }
>> + spin_unlock(&pruss->lock);
>
> This is almost the exact same code as for the DA8XX_PRUCORE_0 case.
> Please be a little more creative in order to avoid such code duplication.

SG - Ok, cleanup done.


>> +
>> + for (loop = 0; loop < bytestowrite; loop++)
>> + __raw_writeb(*pdatatowrite++, paddresstowrite++);
>> +
>> + return 0;
>> +}
>> +EXPORT_SYMBOL(pruss_writeb);
>
> I would recommend providing a simpler variant of your all I/O accessors,
> which write a single word. Most of the users of these simply
> pass bytestowrite=1 anyway, so the caller can become more readable.

SG - At some sections in the code I am using upto 8 bytescount.
            If its ok, I would want to keep it as is.

>
> Also, my comments about __raw_* and Marc's comments about the
> type cast apply to all of these.

SG - Changed to iowrite32 variants and also used make C=1


>> + err = mfd_add_devices(dev, 0, &cell, 1, NULL, 0);
>> + if (err) {
>> + dev_err(dev, "cannot add mfd cells\n");
>> + return err;
>> + }
>> + dev_info(dev, "mfd: added %s device\n",
>> + dev_data[count].dev_name);
>> + }
>> +
>> + return err;
>> +}
>
> This would get much simpler if you just replaced the da8xx_pruss_devices
> array with an mfd_cell array.

SG - Will do. 

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