netdev - Re: [MeeGo-Dev][PATCH v3] Topcliff: Update PCH

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Message-ID: <4CB5931E.8030103@grandegger.com>
Date:	Wed, 13 Oct 2010 13:08:14 +0200
From:	Wolfgang Grandegger <wg@...ndegger.com>
To:	Masayuki Ohtake <masa-korg@....okisemi.com>
CC:	joel.clark@...el.com,
	Tomoya MORINAGA <morinaga526@....okisemi.com>,
	kok.howg.ewe@...el.com, yong.y.wang@...el.com,
	margie.foster@...el.com, qi.wang@...el.com,
	andrew.chih.howe.khor@...el.com, linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org, socketcan-core@...ts.berlios.de,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Barry Song <21cnbao@...il.com>,
	Christian Pellegrin <chripell@...e.org>,
	Wolfram Sang <w.sang@...gutronix.de>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [MeeGo-Dev][PATCH v3] Topcliff: Update PCH_CAN driver to 2.6.35

On 10/13/2010 12:09 PM, Masayuki Ohtake wrote:
> On Thursday, September 30, 2010 6:10 PM, Wolfgang Grandegger wrote:
> 
>>
>> + iowrite32(num, &(priv->regs)->if2_creq);
>> + while (counter) {
>>> + if2_creq = (ioread32(&(priv->regs)->if2_creq)) &
>>> +      CAN_IF_CREQ_BUSY;
>>> + if (!if2_creq)
>>> + break;
>>> + counter--;
>>> + }
>>> + if (!counter)
>>> + dev_err(&priv->ndev->dev, "IF2 BUSY Flag is set forever.\n");
>>> +}
>>
>> Duplicated code!
> 
> No.
> These are not the same.

Of course they are not the same. The only difference is the register
offset (of if1 or if2). A common function with a pointer to the if
register as argument makes sense.

> Though it is possible to integrate to one function by adding parameter,
> I think, current two function method is more easily to read.

I disagree.

>>
>>
>>
>>> + if (status & PCH_STUF_ERR)
>>> + cf->data[2] |= CAN_ERR_PROT_STUFF;
>>> +
>>> + if (status & PCH_FORM_ERR)
>>> + cf->data[2] |= CAN_ERR_PROT_FORM;
>> +
>> + if (status & PCH_ACK_ERR)
>> + cf->data[2] |= CAN_ERR_PROT_LOC_ACK | CAN_ERR_PROT_LOC_ACK_DEL;
>> +
>> + if ((status & PCH_BIT1_ERR) || (status & PCH_BIT0_ERR))
>> + cf->data[2] |= CAN_ERR_PROT_BIT;
>> +
>> + if (status & PCH_CRC_ERR)
>> + cf->data[2] |= CAN_ERR_PROT_LOC_CRC_SEQ |
>> + CAN_ERR_PROT_LOC_CRC_DEL;
>> +
>> + if (status & PCH_LEC_ALL)
>> + iowrite32(status | PCH_LEC_ALL,
>> +   &(priv->regs)->stat);

Well, if status==7 (PCH_LEC_ALL), all of the above conditions are true
as well... convinced now?

>> A bit-wise test of the above values is wrong, I believe. Please use the
>> switch statement instead.
> 
> The above conditions are not only one time.
> I think "switch" is not suitable for the above.
> Thus, current "if" processing is better.

I don't understand! The Last Error Code (LEC) can have values from 0 to
7. A "switch" statement is therefore the right choice. Or have I missed
something.

>>
>>
>> + u32 brp;
>> +
>> + pch_can_get_run_mode(priv, &curr_mode);
>> + if (curr_mode == PCH_CAN_RUN)
>> + pch_can_set_run_mode(priv, PCH_CAN_STOP);
>>
>> The device is stopped when this function is called. Please remove.
> 
> No.
> The above is necessary.

Yes, because you started the device *too early* in pch_can_open() called
by pch_open(). See my other related comments of my previous mail.

> Because this is our HW specification.
> Before setting bitrate, run-mode must be "STOP".

I think it can be avoided easily.

>>
>>
>> +static netdev_tx_t pch_xmit(struct sk_buff *skb, struct net_device *ndev)
>> +{
>> + canid_t id;
>> + u32 id1 = 0;
>> + u32 id2 = 0;
>>
>> Need these values to be preset?
> 
> These values are not essential.
> But these help a engineer to read this code.

I disagree.

>> + /* Enable CAN Interrupts */
>> + pch_can_set_int_custom(priv);
>> +
>> + /* Restore Run Mode */
>> + pch_can_set_run_mode(priv, PCH_CAN_RUN);
>> +
>> + return retval;
>> +}
>>
>> Are the suspend and resume functions tested?
>>
> Yes, we tested before.
> 
> =========================================
> 
> Except the above, we are modifying for your indications.
> 
> I will resubmit soon.

Thanks,

Wolfgang.
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