linux-kernel - Re: [PATCH v3 0/8] usb: ulpi: remove "dev" field from struct ulpi

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Date:   Mon, 29 Aug 2016 10:58:25 +0300
From:   Felipe Balbi <balbi@...nel.org>
To:     Tal Shorer <tal.shorer@...il.com>, gregkh@...uxfoundation.org,
        linux-usb@...r.kernel.org, heikki.krogerus@...ux.intel.com
Cc:     linux-kernel@...r.kernel.org, Tal Shorer <tal.shorer@...il.com>
Subject: Re: [PATCH v3 0/8] usb: ulpi: remove "dev" field from struct ulpi_ops


Hi folks,

Tal Shorer <tal.shorer@...il.com> writes:
> struct ulpi_ops is defined as follows:
>
> struct ulpi_ops {
>         struct device *dev;
>         int (*read)(struct ulpi_ops *ops, u8 addr);
>         int (*write)(struct ulpi_ops *ops, u8 addr, u8 val);
> };
>
> Upon calling ulpi_register_interface(), the struct device argument is
> put inside the struct ulpi_ops argument's dev field. Later, when
> calling the actual read()/write() operations, the struct ulpi_ops is
> passed to them and they use the stored device to access whatever
> private data they need.
>
> This means that if one wishes to reuse the same oprations for multiple
> interfaces (e.g if we have multiple instances of the same controller),
> any but the last interface registered will not operate properly (and
> the one that does work will be at the mercy of the others to not mess
> it up).
>
> I understand that barely any driver uses this bus right now, but I
> suppose it's there to be used at some point. We might as well fix the
> design here before we hit this bug.
>
> This series fixes this by passing the given struct device directly to
> the operation functions via ulpi->dev.parent in ulpi_read() and
> ulpi_write(). It also changes the operations struct to be constant
> since now nobody has a reason to modify it.
>
> Changes from v1:
>  * Split the actual api change into multiple patch as per Felipe Balbi's
>    suggestion. The series now first adds the new api, then migrates
>    everything to use and only then removes the old api.
>
> Changes from v2:
>  * Merge patches 2 and 3 (now patch 2)
>  * Merge patches 5 and 6 (now patch 4)
>  * Remove comment documenting the removed dev field in struct ulpi_ops
>
> Tal Shorer (8):
>   usb: ulpi: move setting of ulpi->dev parent up in ulpi_register()
>   usb: ulpi: add new api functions, {read|write}_dev()
>   usb: dwc3: ulpi: use new api
>   usb: ulpi: remove calls to old api callbacks
>   usb: ulpi: rename operations {read|write}_dev to simply {read|write}
>   usb: ulpi: remove "dev" field from struct ulpi_ops
>   usb: ulpi: make ops struct constant
>   usb: dwc3: ulpi: make dwc3_ulpi_ops constant

I have no idea how to apply these :-) Many of the patches touch dwc3,
but some touch common ulpi. Greg, is it okay if I take the entire series
and send it to you during my for-next pull request?

-- 
balbi

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