Re: [RFC][PATCH] crypto: caam - Add missing MODULE_ALIAS

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On 9/17/21 7:30 PM, Krzysztof Kozlowski wrote:
On 17/09/2021 18:21, Krzysztof Kozlowski wrote:
On 17/09/2021 16:44, Horia Geantă wrote:
On 9/17/2021 1:33 PM, Krzysztof Kozlowski wrote:
On 17/09/2021 11:51, Horia Geantă wrote:
On 9/16/2021 5:06 PM, Marek Vasut wrote:
On 9/16/21 3:59 PM, Krzysztof Kozlowski wrote:
On 16/09/2021 15:41, Marek Vasut wrote:
Add MODULE_ALIAS for caam and caam_jr modules, so they can be auto-loaded.

Signed-off-by: Marek Vasut <marex@xxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Horia Geantă <horia.geanta@xxxxxxx>
Cc: Iuliana Prodan <iuliana.prodan@xxxxxxx>
Cc: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
---
   drivers/crypto/caam/ctrl.c | 1 +
   drivers/crypto/caam/jr.c   | 1 +
   2 files changed, 2 insertions(+)


Since you marked it as RFC, let me share a comment - would be nice to
see here explanation why do you need module alias.

Drivers usually do not need module alias to be auto-loaded, unless the
subsystem/bus reports different alias than one used for binding. Since
the CAAM can bind only via OF, I wonder what is really missing here. Is
it a MFD child (it's one of cases this can happen)?

I noticed the CAAM is not being auto-loaded on boot, and then I noticed
the MODULE_ALIAS fixes cropping up in the kernel log, but I couldn't
find a good documentation for that MODULE_ALIAS. So I was hoping to get
a feedback on it.

What platform are you using?

"make modules_install" should take care of adding the proper aliases,
relying on the MODULE_DEVICE_TABLE() macro in the caam, caam_jr drivers.

modules.alias file should contain:
alias of:N*T*Cfsl,sec4.0C* caam
alias of:N*T*Cfsl,sec4.0 caam
alias of:N*T*Cfsl,sec-v4.0C* caam
alias of:N*T*Cfsl,sec-v4.0 caam
alias of:N*T*Cfsl,sec4.0-job-ringC* caam_jr
alias of:N*T*Cfsl,sec4.0-job-ring caam_jr
alias of:N*T*Cfsl,sec-v4.0-job-ringC* caam_jr
alias of:N*T*Cfsl,sec-v4.0-job-ring caam_jr

Marek added a platform alias which is not present here on the list
(because there are no platform device IDs). The proper question is who
requests this device via a platform match? Who sends such event?

AFAICS the platform bus adds the "platform:" alias to uevent env.
in its .uevent callback - platform_uevent().

When caam (platform) device is added, the uevent is generated with this env.,
which contains both OF-style and "platform:" modaliases.

I am not saying about theoretical case, I know that platform bus will
send platform uevent. How did this device end up in platform bus so this
uevent is being sent? It should be instantiated from OF on for example
amba bus or directly from OF FDT scanning.

Therefore I have the same question - who requests device via a platform
match? Is it used out-of-tree in different configuration?

I tried to reproduce such situation in case of a board I have with me
(Exynos5422). I have a platform_driver only with of_device_id table. The
driver is built as module. In my DTS the device node is like
(exynos5.dtsi and device is modified exynos-chipid to be a module):

        soc: soc {
                 compatible = "simple-bus";
                 #address-cells = <1>;
                 #size-cells = <1>;
                 ranges;

                 chipid: chipid@10000000 {
                         compatible = "samsung,exynos4210-chipid";
                         reg = <0x10000000 0x100>;
                 };

		...
	};

The module was properly autoloaded (via OF aliases/events) and device
was matched.

Please put this on hold for a bit, I need a colleague to check the udev event on this platform before we can move on any further.



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