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From:   Jernej =?utf-8?B?xaBrcmFiZWM=?= <jernej.skrabec@gmail.com>
To:     Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Chen-Yu Tsai <wens@csie.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Samuel Holland <samuel@sholland.org>
Cc:     iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
        linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, Maxime Ripard <mripard@kernel.org>,
        Samuel Holland <samuel@sholland.org>
Subject: Re: [PATCH v2 2/6] iommu/sun50i: Track masters attached to the domain
Date:   Wed, 04 Jan 2023 23:04:43 +0100
Message-ID: <8201525.NyiUUSuA9g@jernej-laptop>
In-Reply-To: <20230103010903.11181-3-samuel@sholland.org>
References: <20230103010903.11181-1-samuel@sholland.org>
 <20230103010903.11181-3-samuel@sholland.org>
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Dne torek, 03. januar 2023 ob 02:08:59 CET je Samuel Holland napisal(a):
> The refcount logic here is broken. The refcount is initialized to 1 with
> no devices attached, so it will be decremented back to 1 when the last
> device is detached. However, refcount_dec_and_test() returns true only
> when the refcount gets decremented to zero, so the domain will never be
> cleaned up, and the hardware will never be disabled.
> 
> Replace the refcount with a mask of masters attached to the domain. The
> domain can be cleaned up when the last master detaches. This mask is
> also necessary to correctly set the bypass register.
> 
> Fixes: 4100b8c229b3 ("iommu: Add Allwinner H6 IOMMU driver")
> Signed-off-by: Samuel Holland <samuel@sholland.org>

Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>

Best regards,
Jernej