linux-kernel - Re: [tpmdd-devel] [PATCH v2] tpm: Add support for new Infineon I2C TPM (SLB 9645 TT 1.2 I2C)

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Message-Id: <201303042054.16849.PeterHuewe@gmx.de>
Date:	Mon, 4 Mar 2013 20:54:16 +0100
From:	Peter Hüwe <PeterHuewe@....de>
To:	tpmdd-devel@...ts.sourceforge.net
Cc:	Kent Yoder <key@...ux.vnet.ibm.com>,
	Peter Huewe <peter.huewe@...ineon.com>,
	linux-security-module@...r.kernel.org, shpedoikal@...il.com,
	linux-kernel@...r.kernel.org
Subject: Re: [tpmdd-devel] [PATCH v2] tpm: Add support for new Infineon I2C TPM (SLB 9645 TT 1.2 I2C)

Hi Kent,

short reply from my private account - so only talking on behalf of myself.

Am Montag, 4. März 2013, 18:41:04 schrieb Kent Yoder:
> Hi Peter,
> 
>   Sorry for the long delay in getting this reviewed...
No problem.

> 
> > -	for (count = 0; count < MAX_COUNT; count++) {
> > -		usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
> > -		rc = __i2c_transfer(tpm_dev.client->adapter, &msg2, 1);
> > -		if (rc > 0)
> > -			break;
> > +	if (tpm_dev.chip_type == SLB9645) {
> > +		/* use a combined read for newer chips
> > +		 * unfortunately the smbus functions are not suitable due to
> > +		 * the 32 byte limit of the smbus.
> > +		 * retries should usually not be needed, but are kept just to
> > +		 * be on the safe side.
> > +		*/
> 
>   Bump out that last line of comment by a column.

You mean I should add 1 space - okay, no problem.
(and I'm nitty picky.... ;) *g*


> > 
> >  	if (rc <= 0)
> >  	
> >  		return -EIO;
> 
>  This confused me for a second, but I see __i2c_transfer returns the number
> of messages transferred. Maybe worth adding a comment.

Maybe I can add one - I'll think about it.


> > 
> > +
> > +#ifdef CONFIG_OF
> > +static const struct of_device_id tpm_tis_i2c_of_match[] = {
> > +	{ .compatible = "infineon,tpm_i2c_infineon", .data = (void *)0 },
> > +	{ .compatible = "infineon,slb9635tt", .data = (void *)0 },
> > +	{ .compatible = "infineon,slb9645tt", .data = (void *)1 },
> 
>   Here "name" and "type" are left empty in of_device_id. Will there be
> times when those are needed? Like informational messages from the OF
> subsystem?

Hmm, what do you propose?
name = chip type ? or name = tpm_i2c_infineon?
type = tpm ?



> > 
> > +		   .of_match_table = of_match_ptr(tpm_tis_i2c_of_match),
> 
>   Please put this line inside an ifdef CONFIG_OF, since of_match_ptr
> lives in there.
NACK.
of.h has already the ifdef CONFIG_OF for of_match_ptr and defines it either as 

#define of_match_ptr(_ptr)      (_ptr)
or
#define of_match_ptr(_ptr)      NULL
depending on CONFIG_OF is set.



>   Won't you also need to add OF to Kconfig?
Not really, as the only stuff we're using is the compatible id - the driver can 
live without it and can be probed from userspace or plain old platform data.
I probably have compile tested it with and without CONFIG_OF.


Is it worth a v3?
 or a small update patch which adds the of name/type and the space? (I can 
create this patch immediately)


Thanks,
Peter



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