[U-Boot] QUERY:U-boot DM:SERIAL:Multiple On-chip UART Controller Support

[Simon Glass]

On 23 May 2018 at 11:56, Vabhav Sharma <vabhav.sharma at nxp.com> wrote:
> Hello Everyone,
>
> I am working on integrating  generic PL011 driver in u-boot and linux for
> ARMv8 NXP SoC and facing issue with multiple UART console enablement in
> u-boot using DM model
>
> Kindly provide your valuable feedback and experts comments.
>
>
>
> DTS require stdout-path(e.g-UART0) to the /chosen device tree node
> ,Accordingly controller(UART0) is probed/initialized as boot console
>
> On u-boot prompt, Bootargs is modified to use UART1(ttyAMA1) console for
> linux boot but kernel hangs after “Starting kernel ... print”
>
>
>
> After debugging it’s found that UART1 is not initialized and single(first)
> controller is  probed/initialized in u-boot (Irrespective of 4 UART nodes
> are enabled in dts)
>
> In drivers/serial/serial-uclass.c ,gd->cur_serial_dev is updated to the DT
> stdout-path or CONFIG_CONS_INDEX or platform data(first index)
>
>
>
> Does the u-boot DM model support only one or multiple UART driver
> probing/initialization? Is there any configuration parameter required to
> define number of UART controllers to be probed/initialized.
>
> This looks limitation as same boot console is used for u-boot and linux and
> unable to use all available UART controllers.
>
>
>
> I am new to u-boot and please correct any misunderstanding
>
> Let me know If I can submit a patch for multiple UART probe in serial-uclass
> or open a bug for multiple UART support in u-boot DM model
>
>
>
> PS:I am unable to find owner of serial uclass driver from MAINTAINERS file
>
>
>
> Regards,
>
> Vabhav
>
>