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Subject: Re: [PATCH v2] clk: bcm2835: Do not use prediv with bcm2711's PLLs
To:     Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
        Ray Jui <rjui@broadcom.com>,
        Scott Branden <sbranden@broadcom.com>,
        bcm-kernel-feedback-list@broadcom.com,
        Eric Anholt <eric@anholt.net>,
        Stefan Wahren <wahrenst@gmx.net>,
        Matthias Brugger <mbrugger@suse.com>
Cc:     pbrobinson@gmail.com, kernel-list@raspberrypi.com,
        Nathan Chancellor <natechancellor@gmail.com>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>, linux-clk@vger.kernel.org,
        linux-rpi-kernel@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
References: <20200730182619.23246-1-nsaenzjulienne@suse.de>
From:   Florian Fainelli <f.fainelli@gmail.com>
Message-ID: <e49faaf7-405d-c54e-ac7d-85296fef284e@gmail.com>
Date:   Thu, 30 Jul 2020 20:51:59 -0700
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On 7/30/2020 11:26 AM, Nicolas Saenz Julienne wrote:
> Contrary to previous SoCs, bcm2711 doesn't have a prescaler in the PLL
> feedback loop. Bypass it by zeroing fb_prediv_mask when running on
> bcm2711.
> 
> Note that, since the prediv configuration bits were re-purposed, this
> was triggering miscalculations on all clocks hanging from the VPU clock,
> notably the aux UART, making its output unintelligible.
> 
> Fixes: 42de9ad400af ("clk: bcm2835: Add BCM2711_CLOCK_EMMC2 support")
> Reported-by: Nathan Chancellor <natechancellor@gmail.com>
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
-- 
Florian