From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Daney Subject: Re: [PATCH 1/3] of: Add prefix parameter to of_modalias_node(). Date: Tue, 22 May 2012 12:45:06 -0700 Message-ID: <4FBBECC2.10503@gmail.com> References: <1336773923-17866-1-git-send-email-ddaney.cavm@gmail.com> <1336773923-17866-2-git-send-email-ddaney.cavm@gmail.com> <20120520055436.13AF03E03B8@localhost> <20120520060802.03CE73E03B8@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: David Daney , "devicetree-discuss@lists.ozlabs.org" , Rob Herring , "spi-devel-general@lists.sourceforge.net" , "linux-kernel@vger.kernel.org" , "linux-mips@linux-mips.org" , "linux-doc@vger.kernel.org" , Liam Girdwood , Tabi Timur-B04825 , Mark Brown , Jaroslav Kysela , Takashi Iwai , "alsa-devel@alsa-project.org" , "linuxppc-dev@lists.ozlabs.org" To: Grant Likely Return-path: In-Reply-To: <20120520060802.03CE73E03B8@localhost> Sender: linux-doc-owner@vger.kernel.org List-Id: linux-spi.vger.kernel.org On 05/19/2012 11:08 PM, Grant Likely wrote: > On Sat, 19 May 2012 23:54:36 -0600, Grant Likely wrote: >> On Fri, 11 May 2012 15:05:21 -0700, David Daney wrote: >>> From: David Daney >>> >>> 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 >> >> 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. >