linux-kernel - Re: [PATCH RESEND 2/2] serial: 8250: omap: Move pm_runtime_get

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Message-ID: <20241012142705.45948f7d@akair>
Date: Sat, 12 Oct 2024 14:27:05 +0200
From: Andreas Kemnade <andreas@...nade.info>
To: Judith Mendez <jm@...com>
Cc: Santosh Shilimkar <ssantosh@...nel.org>, Kevin Hilman
 <khilman@...nel.org>, Linus Walleij <linus.walleij@...aro.org>, Bartosz
 Golaszewski <brgl@...ev.pl>, <linux-omap@...r.kernel.org>,
 <linux-gpio@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Bin Liu
 <b-liu@...com>, <linux-serial@...r.kernel.org>
Subject: Re: [PATCH RESEND 2/2] serial: 8250: omap: Move pm_runtime_get_sync

Am Fri, 11 Oct 2024 12:33:56 -0500
schrieb Judith Mendez <jm@...com>:

> Currently in omap_8250_shutdown, the dma->rx_running
> flag is set to zero in omap_8250_rx_dma_flush. Next
> pm_runtime_get_sync is called, which is a runtime
> resume call stack which can re-set the flag. When the
> call omap_8250_shutdown returns, the flag is expected
> to be UN-SET, but this is not the case. This is causing
> issues the next time UART is re-opened and omap_8250_rx_dma
> is called. Fix by moving pm_runtime_get_sync before the
> omap_8250_rx_dma_flush.
> 
> Signed-off-by: Bin Liu <b-liu@...com>
> Signed-off-by: Judith Mendez <jm@...com>

Is this a theorectical problem or some real practical problem?
So you are running a system with runtime pm enabled on serial
console.
How did you come across this issue?
I could run the serial console/getty with runtime pm autosuspend enabled
without issues all the years.

Regards,
Andreas