Messages in this thread | | | Date | Tue, 22 May 2012 12:45:06 -0700 | From | David Daney <> | Subject | Re: [PATCH 1/3] of: Add prefix parameter to of_modalias_node(). |
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On 05/19/2012 11:08 PM, Grant Likely wrote: > On Sat, 19 May 2012 23:54:36 -0600, Grant Likely<grant.likely@secretlab.ca> wrote: >> On Fri, 11 May 2012 15:05:21 -0700, David Daney<ddaney.cavm@gmail.com> wrote: >>> From: David Daney<david.daney@cavium.com> >>> >>> When generating MODALIASes, it is convenient to add things like "spi:" >>> or "i2c:" to the front of the strings. This allows the standard >>> modprobe to find the right driver when automatically populating bus >>> children from the device tree structure. >>> >>> Add a prefix parameter, and adjust callers. For >>> of_register_spi_devices() use the "spi:" prefix. >>> >>> Signed-off-by: David Daney<david.daney@cavium.com> >> >> Applied, thanks. Some notes below... > > Wait... why is this necessary?
Because in of_register_spi_devices() in of_spi.c, you do:
request_module(spi->modalias);
The string passed to request_module() must have the "spi:" prefix.
> The module type prefix isn't stored in > the modalias value for any other bus type as far as I can see,
It is only useful with the prefix, so I though I would add it to the stored value.
> and > with this series it appears that the "spi:" prefix may or may not be > present in the modalias. That doesn't look right.
Perhaps, but the with the combination of patches 1/3 and 2/3 I tried to ensure that the prefix would always be present for SPI devices.
> > Why isn't prefixing spi: at uevent time sufficient?
Because udev may not be loading the driver.
> IIUC, modprobe > depends on either UEVENT or the modalias attribute to know which > driver to probe. It does look like the attribute is missing the spi: > prefix though. Does the following change work instead of these two > patches? >
No.
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c > index 3d8f662..da8aac7 100644 > --- a/drivers/spi/spi.c > +++ b/drivers/spi/spi.c > @@ -51,7 +51,7 @@ modalias_show(struct device *dev, struct device_attribute *a, char *buf) > { > const struct spi_device *spi = to_spi_device(dev); > > - return sprintf(buf, "%s\n", spi->modalias); > + return sprintf(buf, "%s%s\n", SPI_MODULE_PREFIX, spi->modalias); > } > > So, I've dropped this patch from my tree. If the change above works > for you then I'll push it out. > > g. >
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