linux-kernel - Re: [PATCH] serial: 8250_bcm7271: Fix arbitration handling

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Message-ID: <e75a1c0f-886e-fd89-0876-dc883f75c809@gmail.com>
Date:   Thu, 9 Mar 2023 11:07:03 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Doug Berger <opendmb@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Al Cooper <alcooperx@...il.com>
Cc:     Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Jiri Slaby <jirislaby@...nel.org>,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] serial: 8250_bcm7271: Fix arbitration handling

On 3/9/23 11:02, Doug Berger wrote:
> The arbitration of the UART DMA is mishandled for a few
> exceptional cases when probing and releasing the driver.
> 
> It is possible that the DMA register spaces are not defined in
> device tree for an instance of the driver, so attempts to access
> the registers in brcmuart_arbitration() would use NULL pointers.
> 
> It is also possible for the probe function to return an error
> while still holding the UART DMA. This would prevent the UART
> DMA from being claimed by an instance that could use it.
> 
> These errors are addressed by only releasing the UART DMA if it
> is held by this instance (i.e. priv->dma_enabled == 1) and
> directing early error paths in probe to this common release_dma
> handling.
> 
> Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver")
> Signed-off-by: Doug Berger <opendmb@...il.com>

Acked-by: Florian Fainelli <f.fainelli@...il.com>
-- 
Florian