linux-kernel - Re: [PATCH 1/1] spi: altera: Change to dynamic allocation of spi id

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Date:   Wed, 20 Oct 2021 09:35:11 +0800
From:   Xu Yilun <yilun.xu@...el.com>
To:     Russ Weight <russell.h.weight@...el.com>
Cc:     broonie@...nel.org, linux-spi@...r.kernel.org,
        linux-kernel@...r.kernel.org, trix@...hat.com, lgoncalv@...hat.com,
        hao.wu@...el.com, matthew.gerlach@...el.com
Subject: Re: [PATCH 1/1] spi: altera: Change to dynamic allocation of spi id

On Mon, Oct 18, 2021 at 05:27:38PM -0700, Russ Weight wrote:
> If there are no concerns with this patch, it will need to have the "cc stable"
> tag added for earlier kernels.

The code is good to me, and please add the cc stable tag.

> 
> I don't think it needs a "Fixes" tag, as the problem has been there since the
> driver was introduced.

You could add the Fixes tag for the patches that introduce the drivers.

> 
> Thanks,
> - Russ
> 
> On 10/18/21 5:24 PM, Russ Weight wrote:
> > The spi-altera driver has two flavors: platform and dfl. I'm seeing
> > a case where I have both device types in the same machine, and they
> > are conflicting on the SPI ID:
> >
> > ... kernel: couldn't get idr
> > ... kernel: WARNING: CPU: 28 PID: 912 at drivers/spi/spi.c:2920 spi_register_controller.cold+0x84/0xc0a
> >
> > Both the platform and dfl drivers use the parent's driver ID as the SPI
> > ID. In the error case, the parent devices are dfl_dev.4 and
> > subdev_spi_altera.4.auto. When the second spi-master is created, the
> > failure occurs because the SPI ID of 4 has already been allocated.
> >
> > Change the ID allocation to dynamic (by initializing bus_num to -1) to
> > avoid duplicate SPI IDs.
> >
> > Signed-off-by: Russ Weight <russell.h.weight@...el.com>

Please add the tags and then,
Acked-by: Xu Yilun <yilun.xu@...el.com>

Thanks,
Yilun

> > ---
> >  drivers/spi/spi-altera-dfl.c      | 2 +-
> >  drivers/spi/spi-altera-platform.c | 2 +-
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/spi/spi-altera-dfl.c b/drivers/spi/spi-altera-dfl.c
> > index 44fc9ee13fc7..ca40923258af 100644
> > --- a/drivers/spi/spi-altera-dfl.c
> > +++ b/drivers/spi/spi-altera-dfl.c
> > @@ -134,7 +134,7 @@ static int dfl_spi_altera_probe(struct dfl_device *dfl_dev)
> >  	if (!master)
> >  		return -ENOMEM;
> >  
> > -	master->bus_num = dfl_dev->id;
> > +	master->bus_num = -1;
> >  
> >  	hw = spi_master_get_devdata(master);
> >  
> > diff --git a/drivers/spi/spi-altera-platform.c b/drivers/spi/spi-altera-platform.c
> > index f7a7c14e3679..65147aae82a1 100644
> > --- a/drivers/spi/spi-altera-platform.c
> > +++ b/drivers/spi/spi-altera-platform.c
> > @@ -48,7 +48,7 @@ static int altera_spi_probe(struct platform_device *pdev)
> >  		return err;
> >  
> >  	/* setup the master state. */
> > -	master->bus_num = pdev->id;
> > +	master->bus_num = -1;
> >  
> >  	if (pdata) {
> >  		if (pdata->num_chipselect > ALTERA_SPI_MAX_CS) {