Messages in this thread | | | Date | Tue, 13 Sep 2022 17:16:12 +0200 | From | Sascha Hauer <> | Subject | Re: [PATCH v3] dmaengine: mxs: fix driver registering |
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Hi Vinod,
On Thu, Jun 16, 2022 at 06:58:43AM -0700, Vinod Koul wrote: > On 14-06-22, 12:17, Dario Binacchi wrote: > > Driver registration fails on SOC imx8mn as its supplier, the clock > > control module, is not ready. Since platform_driver_probe(), as > > reported by its description, is incompatible with deferred probing, > > we have to use platform_driver_register(). > > > > Fixes: a580b8c5429a ("dmaengine: mxs-dma: add dma support for i.MX23/28") > > Co-developed-by: Michael Trimarchi <michael@amarulasolutions.com> > > Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com> > > Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com> > > Cc: stable@vger.kernel.org > > > > --- > > > > Changes in v3: > > - Restore __init in front of mxs_dma_init() definition. > > > > Changes in v2: > > - Add the tag "Cc: stable@vger.kernel.org" in the sign-off area. > > > > drivers/dma/mxs-dma.c | 9 +++------ > > 1 file changed, 3 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c > > index 994fc4d2aca4..6e90540fedc4 100644 > > --- a/drivers/dma/mxs-dma.c > > +++ b/drivers/dma/mxs-dma.c > > @@ -741,7 +741,7 @@ static struct dma_chan *mxs_dma_xlate(struct of_phandle_args *dma_spec, > > ofdma->of_node); > > } > > > > -static int __init mxs_dma_probe(struct platform_device *pdev) > > +static int mxs_dma_probe(struct platform_device *pdev) > > why drop __init here, if there is a reason for that please split this > change and document such reason...
The reason for dropping __init comes with this patch. With platform_driver_probe() the probe function is called only once, during init time. The problem with platform_driver_probe() is that the probe function will never be called again when it initially returns -EPROBE_DEFER. That's a problem for Dario: The clock is not yet available, the driver defers probe and will never be probed again when the clock is finally available.
With platform_driver_register() to which this patch switches to the probe function can be called at any time, thus __init has to be removed.
For what it's worth:
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
for this patch.
Sascha
> > > { > > struct device_node *np = pdev->dev.of_node; > > const struct mxs_dma_type *dma_type; > > @@ -839,10 +839,7 @@ static struct platform_driver mxs_dma_driver = { > > .name = "mxs-dma", > > .of_match_table = mxs_dma_dt_ids, > > }, > > + .probe = mxs_dma_probe, > > }; > > > > -static int __init mxs_dma_module_init(void) > > -{ > > - return platform_driver_probe(&mxs_dma_driver, mxs_dma_probe); > > -} > > -subsys_initcall(mxs_dma_module_init); > > +module_platform_driver(mxs_dma_driver); > > -- > > 2.32.0 > > -- > ~Vinod >
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