linux-kernel - Re: [PATCH v2] tpm: cr50: Add new device/vendor ID 0x504a6666

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Date:   Thu, 21 Apr 2022 19:13:43 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Jes Klinke <jbk@...gle.com>
Cc:     Paul Menzel <pmenzel@...gen.mpg.de>,
        "Jes B. Klinke" <jbk@...omium.org>,
        linux-integrity@...r.kernel.org, Jason Gunthorpe <jgg@...pe.ca>,
        Peter Huewe <peterhuewe@....de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] tpm: cr50: Add new device/vendor ID 0x504a6666

On Thu, Apr 21, 2022 at 09:07:21AM -0700, Jes Klinke wrote:
> Dear Paul,
> 
> On Wed, Apr 20, 2022 at 3:52 AM Paul Menzel <pmenzel@...gen.mpg.de> wrote:
> >
> > Dear Jes,
> >
> >
> > Am 20.04.22 um 01:37 schrieb Jes B. Klinke:
> > > Accept one additional numerical value of DID:VID for next generation
> > > Google TPM with new firmware, to be used in future Chromebooks.
> > >
> > > The TPM with the new firmware has the code name TI50, and is going to
> > > use the same interfaces.
> > >
> > > Signed-off-by: Jes B. Klinke <jbk@...omium.org>
> > > Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>
> > > ---
> > >
> > >   drivers/char/tpm/tpm_tis_i2c_cr50.c | 7 ++++---
> > >   1 file changed, 4 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/char/tpm/tpm_tis_i2c_cr50.c b/drivers/char/tpm/tpm_tis_i2c_cr50.c
> > > index f6c0affbb4567..4ddb8ff3a8569 100644
> > > --- a/drivers/char/tpm/tpm_tis_i2c_cr50.c
> > > +++ b/drivers/char/tpm/tpm_tis_i2c_cr50.c
> > > @@ -31,6 +31,7 @@
> > >   #define TPM_CR50_TIMEOUT_SHORT_MS   2               /* Short timeout during transactions */
> > >   #define TPM_CR50_TIMEOUT_NOIRQ_MS   20              /* Timeout for TPM ready without IRQ */
> > >   #define TPM_CR50_I2C_DID_VID                0x00281ae0L     /* Device and vendor ID reg value */
> > > +#define TPM_TI50_I2C_DID_VID         0x504a6666L     /* Device and vendor ID reg value */
> > >   #define TPM_CR50_I2C_MAX_RETRIES    3               /* Max retries due to I2C errors */
> > >   #define TPM_CR50_I2C_RETRY_DELAY_LO 55              /* Min usecs between retries on I2C */
> > >   #define TPM_CR50_I2C_RETRY_DELAY_HI 65              /* Max usecs between retries on I2C */
> > > @@ -742,15 +743,15 @@ static int tpm_cr50_i2c_probe(struct i2c_client *client)
> > >       }
> > >
> > >       vendor = le32_to_cpup((__le32 *)buf);
> > > -     if (vendor != TPM_CR50_I2C_DID_VID) {
> > > +     if (vendor != TPM_CR50_I2C_DID_VID && vendor != TPM_TI50_I2C_DID_VID) {
> > >               dev_err(dev, "Vendor ID did not match! ID was %08x\n", vendor);
> > >               tpm_cr50_release_locality(chip, true);
> > >               return -ENODEV;
> > >       }
> > >
> > > -     dev_info(dev, "cr50 TPM 2.0 (i2c 0x%02x irq %d id 0x%x)\n",
> > > +     dev_info(dev, "%s TPM 2.0 (i2c 0x%02x irq %d id 0x%x)\n",
> > > +              vendor == TPM_TI50_I2C_DID_VID ? "ti50" : "cr50",
> > >                client->addr, client->irq, vendor >> 16);
> > > -
> >
> > Remove this blank line wasn’t needed, I gues.
> 
> You are right, I should probably have left the blank line untouched.
> It does not hurt the readability of the code much to remove it,
> though.

I don't mind removing it.

> 
> > >       return tpm_chip_register(chip);
> > >   }
> > >
> >
> > Thank for addressing the other comments, and congratulations on getting
> > your first commit into the Linux kernel.
> 
> When I think about it, I did propose a kernel patch in 2002, to
> introduce /proc/sys/kernel/core_pattern, so this is my second patch.
> All the mailing lists, and formal review process this time seemed
> daunting at first, though, so thank you for guiding me through the
> process.

It gets easier over time when your patch count increases.

Compared to many Github projects, I find actually contributing to kernel
easier than many of those, because form is so rigid, but this of course
happens over time. I.e. over time you can estimate a lot how likely is
patch get to be accepted.

Also it is good to remember that kernel maintainers might sound a bit
impolite, not because they want to be, but when you review dozens of
patches in a day, you have to be somewhat mechanic how you response,
and simply do not have time to be "verbosely polite".

> Regards
> Jes

BR, Jarkko