linux-kernel - Re: [PATCH] tpm_tis_spi: set default probe function if device id not match

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Message-ID: <YJhIcIXMFj/LcYwu@kernel.org>
Date:   Sun, 9 May 2021 23:39:12 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     乱石 <zhangliguang@...ux.alibaba.com>
Cc:     Peter Huewe <peterhuewe@....de>, Jason Gunthorpe <jgg@...pe.ca>,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tpm_tis_spi: set default probe function if device id not
 match

On Sat, May 08, 2021 at 10:46:57AM +0800, 乱石 wrote:
> Hi,
> 
> 在 2021/5/8 10:01, Jarkko Sakkinen 写道:
> > On Fri, May 07, 2021 at 10:52:55PM +0800, Liguang Zhang wrote:
> > > In DSDT table, TPM _CID was SMO0768, and no _HID definition. After a
> > > kernel upgrade from 4.19 to 5.10, TPM probe function was changed which
> > > causes device probe fails. In order to make newer kernel to be
> > > compatible with the older acpi definition, it would be best set default
> > > probe function.
> > > 
> > > Signed-off-by: Liguang Zhang <zhangliguang@...ux.alibaba.com>
> > > ---
> > >   drivers/char/tpm/tpm_tis_spi_main.c | 12 ++++++++----
> > >   1 file changed, 8 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/drivers/char/tpm/tpm_tis_spi_main.c b/drivers/char/tpm/tpm_tis_spi_main.c
> > > index 3856f6ebcb34..da632a582621 100644
> > > --- a/drivers/char/tpm/tpm_tis_spi_main.c
> > > +++ b/drivers/char/tpm/tpm_tis_spi_main.c
> > > @@ -240,10 +240,14 @@ static int tpm_tis_spi_driver_probe(struct spi_device *spi)
> > >   	tpm_tis_spi_probe_func probe_func;
> > >   	probe_func = of_device_get_match_data(&spi->dev);
> > > -	if (!probe_func && spi_dev_id)
> > > -		probe_func = (tpm_tis_spi_probe_func)spi_dev_id->driver_data;
> > > -	if (!probe_func)
> > > -		return -ENODEV;
> > > +	if (!probe_func) {
> > > +		if (spi_dev_id) {
> > > +			probe_func = (tpm_tis_spi_probe_func)spi_dev_id->driver_data;
> > > +			if (!probe_func)
> > > +				return -ENODEV;
> > Perhaps also hear fallback to tpm_tis_spi_probe?
> 
> 
> Yes, I do not think of a good way. Do you have any suggestions?

So, I just think that when you have this part:


if (!probe_func) {
	if (spi_dev_id) {
                probe_func = (tpm_tis_spi_probe_func)spi_dev_id->driver_data;
                if (!probe_func)
                        return -ENODEV;

Why in here would not you also want to fallback to tpm_tis_spi_probe?

/Jarkko