Re: [PATCH] mfd: wcd934x: set DMA mask on parent to silence "DMA mask not set"

[David Heidelberg]

On 03/09/2026 14:49, Lee Jones wrote:
> On Sun, 23 Aug 2026, David Heidelberg via B4 Relay wrote:
>
> > From: David Heidelberg <david@xxxxxxx>
> >
> > The wcd934x MFD parent (a slim_device) never initializes its
> > dma_mask/coherent_dma_mask. When the DT-aware children pass through
> > of_dma_configure() this triggers the "DMA mask not set" warning for
> > each child.
> >
> > Cc: stable@xxxxxxxxxxxxxxx
> > Fixes: f959dcd6ddfd ("dma-direct: Fix potential NULL pointer dereference")
> > Assisted-by: tencent:hy3
> > Signed-off-by: David Heidelberg <david@xxxxxxx>
> > ---
> >   drivers/mfd/wcd934x.c | 6 ++++++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/mfd/wcd934x.c b/drivers/mfd/wcd934x.c
> > index 3c3080e8c8cf7..70ee13791d52b 100644
> > --- a/drivers/mfd/wcd934x.c
> > +++ b/drivers/mfd/wcd934x.c
> > @@ -1,12 +1,13 @@
> >   // SPDX-License-Identifier: GPL-2.0
> >   // Copyright (c) 2019, Linaro Limited
> >   
> >   #include <linux/clk.h>
> > +#include <linux/dma-mapping.h>
> >   #include <linux/gpio/consumer.h>
> >   #include <linux/interrupt.h>
> >   #include <linux/kernel.h>
> >   #include <linux/mfd/core.h>
> >   #include <linux/mfd/wcd934x/registers.h>
> >   #include <linux/mfd/wcd934x/wcd934x.h>
> >   #include <linux/module.h>
> >   #include <linux/of.h>
> > @@ -212,16 +213,21 @@ static int wcd934x_slim_status(struct slim_device *sdev,
> >   static int wcd934x_slim_probe(struct slim_device *sdev)
> >   {
> >   	struct device *dev = &sdev->dev;
> >   	struct device_node *np = dev->of_node;
> >   	struct wcd934x_ddata *ddata;
> >   	struct gpio_desc *reset_gpio;
> >   	int ret;
> >   
> > +	if (!dev->dma_mask) {
> > +		dev->dma_mask = &dev->coherent_dma_mask;
> > +		dev->coherent_dma_mask = DMA_BIT_MASK(32);
> > +	}
> > +
>
> Any reason not to use dma_coerce_mask_and_coherent()?

Didn't knew about it. Sending v2.

David