linux-kernel - Re: [PATCH 1/2] mfd: ti_am335x_tscadc: Provide unique name for child mfd cells

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Date:   Wed, 28 Nov 2018 11:03:21 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Vignesh R <vigneshr@...com>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-iio@...r.kernel.org, linux-omap@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] mfd: ti_am335x_tscadc: Provide unique name for child
 mfd cells

On Wed, 28 Nov 2018, Vignesh R wrote:

> Hi,
> 
> On 28/11/18 2:37 PM, Lee Jones wrote:
> > On Mon, 19 Nov 2018, Vignesh R wrote:
> > 
> >> Provide unique names for child mfd cells, this is required in order to
> >> support registering of multiple instances of same ti_am335x_tscadc IP.
> > 
> > I don't think it is.  What is the error you are receiving?
> 
> W/o this patch I get:
> 
> [    2.296839] sysfs: cannot create duplicate filename '/bus/platform/devices/TI-am335x-adc'
> [    2.305085] CPU: 0 PID: 31 Comm: kworker/0:1 Not tainted 4.20.0-rc3-next-20181123-00018-g
> 7791ce8f123f-dirty #182
> [    2.315254] Hardware name: Texas Instruments AM654 Base Board (DT)
> [    2.321447] Workqueue: events deferred_probe_work_func
> [    2.326585] Call trace:
> [    2.329036]  dump_backtrace+0x0/0x1c0
> [    2.332699]  show_stack+0x14/0x20
> [    2.336017]  dump_stack+0x9c/0xbc
> [    2.339333]  sysfs_warn_dup+0x60/0x78
> [    2.342995]  sysfs_do_create_link_sd.isra.0+0xdc/0xe8
> [    2.348042]  sysfs_create_link+0x20/0x40
> [    2.351963]  bus_add_device+0x68/0x130
> [    2.355711]  device_add+0x398/0x618
> [    2.359199]  platform_device_add+0x120/0x290
> [    2.363469]  mfd_add_device+0x23c/0x2e8
> [    2.367302]  mfd_add_devices+0xb4/0x158
> [    2.371136]  ti_tscadc_probe+0x35c/0x4c8
> [    2.375056]  platform_drv_probe+0x50/0xa0
> [    2.379062]  really_probe+0x204/0x2a8
> [    2.382722]  driver_probe_device+0x58/0x100
> [    2.386903]  __device_attach_driver+0x98/0xf0
> [    2.391258]  bus_for_each_drv+0x64/0xc8
> [    2.395091]  __device_attach+0xd8/0x138
> [    2.398923]  device_initial_probe+0x10/0x18
> [    2.403103]  bus_probe_device+0x90/0x98
> [    2.406938]  deferred_probe_work_func+0x74/0xb0
> [    2.411470]  process_one_work+0x1e0/0x330
> [    2.415478]  worker_thread+0x238/0x460
> [    2.419225]  kthread+0x128/0x130
> [    2.422452]  ret_from_fork+0x10/0x1c
> [    2.426195] ti_am3359-tscadc: probe of 40210000.tscadc failed with error -1

That's because of the way the cells are being registered:

        err = mfd_add_devices(&pdev->dev, pdev->id, tscadc->cells,
                tscadc->used_cells, NULL, 0, NULL);

The cells are not numbered (tscadc->cells->id is always 0) and you are
forcing the use of the platform ID from the parent platform device
(with pdev->id here).  Instead you should s/pdev->id/PLATFORM_DEVID_AUTO/
or number the cells manually. I suggest the former.

> >> Signed-off-by: Vignesh R <vigneshr@...com>
> >> ---
> >>  drivers/mfd/ti_am335x_tscadc.c | 6 ++++--
> >>  1 file changed, 4 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/mfd/ti_am335x_tscadc.c b/drivers/mfd/ti_am335x_tscadc.c
> >> index c2d47d78705b..ee08af34f81d 100644
> >> --- a/drivers/mfd/ti_am335x_tscadc.c
> >> +++ b/drivers/mfd/ti_am335x_tscadc.c
> >> @@ -248,7 +248,8 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
> >>  	if (tsc_wires > 0) {
> >>  		tscadc->tsc_cell = tscadc->used_cells;
> >>  		cell = &tscadc->cells[tscadc->used_cells++];
> >> -		cell->name = "TI-am335x-tsc";
> >> +		cell->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%s:%s",
> >> +					    dev_name(&pdev->dev), "tsc");
> >>  		cell->of_compatible = "ti,am3359-tsc";
> >>  		cell->platform_data = &tscadc;
> >>  		cell->pdata_size = sizeof(tscadc);
> >> @@ -258,7 +259,8 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
> >>  	if (adc_channels > 0) {
> >>  		tscadc->adc_cell = tscadc->used_cells;
> >>  		cell = &tscadc->cells[tscadc->used_cells++];
> >> -		cell->name = "TI-am335x-adc";
> >> +		cell->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%s:%s",
> >> +					    dev_name(&pdev->dev), "adc");
> >>  		cell->of_compatible = "ti,am3359-adc";
> >>  		cell->platform_data = &tscadc;
> >>  		cell->pdata_size = sizeof(tscadc);
> > 
> 

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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