Messages in this thread | | | From | Rob Herring <> | Date | Mon, 19 Jan 2015 08:11:20 -0600 | Subject | Re: [PATCH v5 5/5] tty/serial: Add Spreadtrum sc9836-uart driver support |
| |
On Mon, Jan 19, 2015 at 3:55 AM, Lyra Zhang <zhang.lyra@gmail.com> wrote: > On Sat, Jan 17, 2015 at 12:41 AM, Rob Herring <robherring2@gmail.com> wrote: >> On Fri, Jan 16, 2015 at 4:00 AM, Chunyan Zhang >> <chunyan.zhang@spreadtrum.com> wrote: >>> Add a full sc9836-uart driver for SC9836 SoC which is based on the >>> spreadtrum sharkl64 platform. >>> This driver also support earlycon. >>> This patch also replaced the spaces between the macros and their >>> values with the tabs in serial_core.h
[...]
>>> +static int __init sprd_serial_init(void) >>> +{ >>> + int ret = 0; >>> + >>> + ret = uart_register_driver(&sprd_uart_driver); >> >> This can be done in probe now. Then you can use module_platform_driver(). >> > > Question: > 1. there are 4 uart ports configured in dt for sprd_serial, so probe > will be called 4 times, but uart_register_driver only needs to be > called one time, so can we use uart_driver.state to check if > uart_register_driver has already been called ?
Yes.
> 2. if I use module_platform_driver() instead of > module_init(sprd_serial_init) and module_exit(sprd_serial_exit) , I > must move uart_unregister_driver() which is now processed in > sprd_serial_exit() to sprd_remove(), there is a similar problem with > probe(), sprd_remove() will also be called 4 times, and actually it > should be called only one time. How can we deal with this case?
Look at pl01x or Samsung UART drivers which have done this conversion.
> 3. for the second question, we can check the platform_device->id, if > it is equal to the index of last port (e.g. 4 for this case), then > uart_unregister_driver() can be called. Does it work correctly? since > for this case, we must keep the order of releasing ports.
The id will not be the line index in the DT case. I don't think you can guarantee the order either.
It would be better to make uart_{un}register_driver deal with being called multiple times so drivers don't have to deal with getting this correct. I'm not sure if that is feasible though.
Rob
| |