Messages in this thread | | | Date | Mon, 15 Aug 2016 15:02:58 +0300 | From | Heikki Krogerus <> | Subject | Re: [PATCH v2 00/10] usb: ulpi: remove "dev" field from struct ulpi_ops |
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Hi,
Please forgive me for taking so long to reply. I just returned from paternal leave.
On Mon, Aug 01, 2016 at 09:15:48PM +0300, Tal Shorer wrote: > 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.
If there are multiple instances of the same controller, the controller driver just needs to provide a separate ops for every one of them. This isn't really a problem as you describe it. But I'm not against API improvements even if they don't fix anything. I'll test these tomorrow.
Thanks,
-- heikki
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