Hi Dmitry,
Is this patch ready to be pushed based on the justification that we bring about it?.
Thanks,
Miguel Aguilar
Narnakaje, Snehaprabha wrote:
[...]
How do you ensure that only one of these drivers is loaded at a time?
Or is the set of supported devices is board-specific (in which case the
board code should have an idea how to properly set the configuration for
the devices that are supported on that board)?
The DM365 EVM has other device that can't coexist with key scan, so this
is a
particular situation. There no way to ensure that one of this modules is
loaded
at time, but using device_enable handler is a proper way to ensure that a
driver
will be loaded properly, the board code can't assume which driver is going
to be
loaded.
I think Sneha, can bring you more details about this particular case.
Ideally PINMUX settings and any other EVM/board related initializations should be done in the board-setup files, when the platform_data for the driver is registered. Our PINMUX configuration APIs do not really have resource management capabilities to remember what drivers/peripherals have taken the resource/bits.
As Miguel mentioned, we have PINMUX conflict between Keyscan lines and the EMIF address lines used by CPLD. PINMUX2 register can only select one of configurations. CPLD is required for the video capture driver which should be enabled all the time in a system. So Miguel in his initial patch called the keyscan_init function within the #ifdef CONFIG_KEYSCAN construct. The keyscan_init function handled the PINMUX configuration for keyscan and also registered the platform_device. The general guideline in the board-setup files is that we should always let platform_device registered. The driver is enabled/disabled anyway using the CONFIG option.
The default configuration for the board does not enable Keyscan. One can test/use kescyan driver by enabling the CONFIG option, but CPLD (video capture input selection, to be specific) configuration will not be available. I would say, it is a limitation in the board/EVM design. Other board designs can have CPLD use different address lines, in which case the CONFIG option can be enabled in the default configuration.
Thanks
Sneha
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