[PATCH v8 08/14] mfd: rk8xx: add rk806 support

[Sebastian Reichel]

Hi Neil,

On Wed, Nov 15, 2023 at 06:17:50PM +0100, Neil Armstrong wrote:
> Hi Sebastian,
> 
> On 04/05/2023 19:36, Sebastian Reichel wrote:
> > Add support for SPI connected rk806, which is used by the RK3588
> > evaluation boards. The PMIC is advertised to support I2C and SPI,
> > but the evaluation boards all use SPI. Thus only SPI support is
> > added here.
> > 
> > Acked-for-MFD-by: Lee Jones <lee at kernel.org>
> > Tested-by: Diederik de Haas <didi.debian at cknow.org> # Rock64, Quartz64 Model A + B
> > Tested-by: Vincent Legoll <vincent.legoll at gmail.com> # Pine64 QuartzPro64
> > Signed-off-by: Sebastian Reichel <sebastian.reichel at collabora.com>
> > ---
> >   drivers/mfd/Kconfig       |  14 ++
> >   drivers/mfd/Makefile      |   1 +
> >   drivers/mfd/rk8xx-core.c  |  69 ++++++-
> >   drivers/mfd/rk8xx-spi.c   | 124 ++++++++++++
> >   include/linux/mfd/rk808.h | 409 ++++++++++++++++++++++++++++++++++++++
> >   5 files changed, 614 insertions(+), 3 deletions(-)
> >   create mode 100644 drivers/mfd/rk8xx-spi.c
> > 
> 
> <snip>
> 
> > -	ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
> > -			      cells, nr_cells, NULL, 0,
> > +	ret = devm_mfd_add_devices(dev, 0, cells, nr_cells, NULL, 0,
> >   			      regmap_irq_get_domain(rk808->irq_data));
> 
> It seems you replaced PLATFORM_DEVID_NONE by 0, triggering again the bug preventing
> having multiples RK pmics on the same system I fixed earlier at [1].

All cells have PLATFORM_DEVID_NONE specified and thus are registered
without an ID. I changed this bit to avoid overriding the
information, since I did not want to have PLATFORM_DEVID_NONE for
rk806.

> This gives (again):
> <4>[ 0.664107] sysfs: cannot create duplicate filename '/bus/platform/devices/rk808-clkout'

Which means, you do not want PLATFORM_DEVID_NONE (-1), but
PLATFORM_DEVID_AUTO (-2). The above path is the expected path
for PLATFORM_DEVID_NONE.

> <4>[ 0.664120] CPU: 3 PID: 97 Comm: kworker/u12:2 Not tainted 6.6.1 #1
> <4>[ 0.664131] Hardware name: Hardkernel ODROID-GO-Ultra (DT)
> <4>[ 0.664139] Workqueue: events_unbound deferred_probe_work_func
> <4>[ 0.664160] Call trace:
> <4>[ 0.664165] dump_backtrace+0x9c/0x11c
> <4>[ 0.664181] show_stack+0x18/0x24
> <4>[ 0.664193] dump_stack_lvl+0x78/0xc4
> <4>[ 0.664205] dump_stack+0x18/0x24
> <4>[ 0.664215] sysfs_warn_dup+0x64/0x80
> <4>[ 0.664227] sysfs_do_create_link_sd+0xf0/0xf8
> <4>[ 0.664239] sysfs_create_link+0x20/0x40
> <4>[ 0.664250] bus_add_device+0x114/0x160
> <4>[ 0.664259] device_add+0x3f0/0x7cc
> <4>[ 0.664267] platform_device_add+0x180/0x270
> <4>[ 0.664278] mfd_add_device+0x390/0x4a8
> <4>[ 0.664290] devm_mfd_add_devices+0xb0/0x150
> <4>[ 0.664301] rk8xx_probe+0x26c/0x410
> <4>[ 0.664312] rk8xx_i2c_probe+0x64/0x98
> <4>[ 0.664323] i2c_device_probe+0x104/0x2e8
> <4>[ 0.664333] really_probe+0x184/0x3c8
> <4>[ 0.664342] __driver_probe_device+0x7c/0x16c
> <4>[ 0.664351] driver_probe_device+0x3c/0x10c
> <4>[ 0.664360] __device_attach_driver+0xbc/0x158
> <4>[ 0.664369] bus_for_each_drv+0x80/0xdc
> <4>[ 0.664377] __device_attach+0x9c/0x1ac
> <4>[ 0.664386] device_initial_probe+0x14/0x20
> <4>[ 0.664395] bus_probe_device+0xac/0xb0
> <4>[ 0.664403] deferred_probe_work_func+0xa0/0xf4
> <4>[ 0.664412] process_one_work+0x1bc/0x378
> <4>[ 0.664421] worker_thread+0x1dc/0x3d4
> <4>[ 0.664429] kthread+0x104/0x118
> <4>[ 0.664440] ret_from_fork+0x10/0x20
> <3>[ 0.664494] rk8xx-i2c 0-001c: error -EEXIST: failed to add MFD devices
> <4>[ 0.666769] rk8xx-i2c: probe of 0-001c failed with error -17

I didn't notice when working on rk806, but after analyzing it now:

Your patch effectively set the cells to PLATFORM_DEVID_AUTO, because
you set all cells to PLATFORM_DEVID_NONE (-1) and additionally used
PLATFORM_DEVID_NONE (-1) for the devm_mfd_add_devices() call. But
that uses the sum of both IDs. Adding -1 to -1 is -2 and thus
PLATFORM_DEVID_AUTO. This is of course very confusing and just
worked by chance. There are two options:

1. Modify all cells to use PLATFORM_DEVID_AUTO instead of
PLATFORM_DEVID_NONE
2. Drop the .id from all cells and use PLATFORM_DEVID_AUTO in the
call to devm_mfd_add_devices()

Note, that switching from PLATFORM_DEVID_NONE to PLATFORM_DEVID_AUTO
modifies sysfs paths and thus might break people's scripts; that's why
I tried not to modify any existing platform. I will let you deal
with that, since I cannot even test any !rk806 platform supported by
this driver :)

Also mfd_add_device should probably get special handling for
PLATFORM_DEVID_NONE, just like it already has special handling
for PLATFORM_DEVID_AUTO.

Greetings,

-- Sebastian
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