linux-kernel - Re: [PATCH v1] of: property: Don't retry device_link

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Message-ID: <6c9db8d92b6702bc5d7b238788e3cb3cf7ab2486.camel@suse.de>
Date:   Fri, 17 Apr 2020 18:50:07 +0200
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     Saravana Kannan <saravanak@...gle.com>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        kernel-team@...roid.com, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] of: property: Don't retry device_link_add() upon
 failure

On Thu, 2020-04-16 at 13:58 -0700, Saravana Kannan wrote:
> When of_link_to_phandle() was implemented initially, there was no way to
> tell if device_link_add() was failing because the supplier device hasn't
> been parsed yet, hasn't been added yet, the links were creating a cycle,
> etc. Some of these were transient errors that'd go away at a later
> point.
> 
> However, with the current set of improved checks, if device_link_add()
> fails, it'll only be for permanent errors like cycles or out-of-memory
> errors.
> 
> Also, with the addition of DL_FLAG_SYNC_STATE_ONLY flag [1] to device
> links, all the valid dependency cycles due to "proxy" device links
> (needed for correctness of sync_state() device callback) will never fail
> device_link_add() due to cycles.
> 
> So, continuing to retry failing device links (by returning -EAGAIN) is
> no longer useful. At worst, it prevents platforms from setting
> fw_devlink=on (or better) because it prevents proper boot up. So, let's
> not do that anymore.
> 
> [1] - 
> https://lore.kernel.org/lkml/20191028220027.251605-1-saravanak@google.com/
> Cc: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Signed-off-by: Saravana Kannan <saravanak@...gle.com>
> ---

Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>

Thanks!
Nicolas


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