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Date: Thu, 07 May 2026 19:58:32 +0530
Message-Id: <DICIKJZ1JOZQ.36S4SZ5G8RM5Q@disroot.org>
Cc: <linux-mmc@vger.kernel.org>, <devicetree@vger.kernel.org>,
 <linux-kernel@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>,
 <linux-samsung-soc@vger.kernel.org>
Subject: Re: [PATCH v3 0/2] Configuring DMA threshold value for DW-MMC
 controllers
From: "Kaustabh Chakraborty" <kauschluss@disroot.org>
To: "Kaustabh Chakraborty" <kauschluss@disroot.org>, "Ulf Hansson"
 <ulfh@kernel.org>, "Rob Herring" <robh@kernel.org>, "Krzysztof Kozlowski"
 <krzk+dt@kernel.org>, "Conor Dooley" <conor+dt@kernel.org>, "Jaehoon Chung"
 <jh80.chung@samsung.com>, "Shawn Lin" <shawn.lin@rock-chips.com>,
 "Krzysztof Kozlowski" <krzk@kernel.org>, "Alim Akhtar"
 <alim.akhtar@samsung.com>
References: <20260415-dwmmc-dma-thr-v3-0-31014d36b6ee@disroot.org>
In-Reply-To: <20260415-dwmmc-dma-thr-v3-0-31014d36b6ee@disroot.org>

On 2026-04-15 20:32 +05:30, Kaustabh Chakraborty wrote:
> In Samsung Exynos 7870 devices with Broadcom Wi-Fi, it has been observed
> that small sized DMA transfers are unreliable and are not written
> properly, which renders the cache incoherent.
>
> Experimental observations say that DMA transfer sizes of somewhere
> around 64 to 512 are intolerable. We must thus implement a mechanism to
> fall back to PIO transfer in this case. One such approach, which this
> series implements is allowing the DMA transfer threshold, which is
> already defined in the driver, to be configurable.
>
> Note that this patch is likely to be labelled as a workaround. These
> smaller transfers seem to be successful from downstream kernels,
> however efforts to figure out how so went in vain. It is also very
> possible that the downstream Broadcom Wi-Fi SDIO driver uses PIO
> transfers as well.
>
> Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>

Hi, bump! What's the status of this patch series? Both patches have been
reviewed.