Re: [REQUEST] Backport 8250_dw BUSY deassert series to 6.12.y stable

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, May 08, 2026 at 06:16:14PM +0300, Ionut Nechita (Wind River) wrote:
> From: Ionut Nechita <ionut.nechita@windriver.com>
> 
> Hi Ilpo, Greg,
> 
> We're running kernel 6.12 (LTS) on production systems with DesignWare
> 8250 UARTs and are hitting the BUSY assertion issue that your recent
> series addresses in 6.18:
> 
>   Ilpo Järvinen (7):
>     serial: 8250: Protect LCR write in shutdown
>     serial: 8250_dw: Avoid unnecessary LCR writes
>     serial: 8250: Add serial8250_handle_irq_locked()
>     serial: 8250_dw: Rework dw8250_handle_irq() locking and IIR handling
>     serial: 8250_dw: Rework IIR_NO_INT handling to stop interrupt storm
>     serial: 8250: Add late synchronize_irq() to shutdown to handle DW UART BUSY
>     serial: 8250_dw: Ensure BUSY is deasserted
> 
> Patch 7/7 has Cc: stable, but it depends on patches 1-6 for the new
> infrastructure (serial8250_handle_irq_locked(), the reworked locking in
> dw8250_handle_irq(), etc.).
> 
> Could the full series be nominated for 6.12.y stable backport?  Or if
> that's too invasive for stable, could you advise on the minimal subset
> that would allow patch 7 to apply cleanly on 6.12?

Why not just move to 6.18.y instead if you have this issue?

thanks,

greg k-h