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(unknown [112.65.126.162]) by smtp.qiye.163.com (Hmail) with ESMTP id 31bc9a766; Fri, 23 Jan 2026 17:53:52 +0800 (GMT+08:00) From: Albert Yang To: Ulf Hansson , Adrian Hunter , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Ge Gordon , Arnd Bergmann Cc: BST Linux Kernel Upstream Group , linux-mmc@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Albert Yang Subject: [PATCH v5 2/6] mmc: sdhci: allow drivers to pre-allocate bounce buffer Date: Fri, 23 Jan 2026 17:53:38 +0800 Message-ID: <20260123095342.272505-3-yangzh0906@thundersoft.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260123095342.272505-1-yangzh0906@thundersoft.com> References: <20260123095342.272505-1-yangzh0906@thundersoft.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-HM-Tid: 0a9bea46453109cckunm2b675df11c3da1 X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFITzdXWS1ZQUlXWQ8JGhUIEh9ZQVkZTEMfVh5DSkgYGEpLSkNDTFYVFAkWGhdVEwETFh oSFyQUDg9ZV1kYEgtZQVlKSklVTU5VSklNVUpNSVlXWRYaDxIVHRRZQVlPS0hVSktJT09PSFVKS0 tVSkJLS1kG DKIM-Signature: a=rsa-sha256; b=PzvIHpSCmK66dnvT0ft3KvRFx+FVWMdDumgNLodw9BVs7lOxgoh81nvrT0KCoMJqz8L8eNyIwfuNB4bhONpWIZ+G0AqA5JJ2/vOyG4Oe+e+C4AEHLXBTQEPxAJOG/Vf8H7+gucus8ETIsdzOM31xnEvN7A3xPAMbrfZaa7eEadA=; c=relaxed/relaxed; s=default; d=thundersoft.com; v=1; bh=gJkNXHiazd0dwH31jEBkLazzm2uWsRVuYgNsDwicVtY=; h=date:mime-version:subject:message-id:from; X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260123_015359_491856_4F1D07CB X-CRM114-Status: GOOD ( 12.00 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Allow platform drivers to pre-allocate bounce buffer by checking if host->bounce_buffer is already set before attempting allocation. This enables platforms with specific DMA constraints (such as 32-bit DMA on controllers that cannot access high memory) to use their own reserved memory regions for the bounce buffer. Suggested-by: Adrian Hunter Signed-off-by: Albert Yang Acked-by: Adrian Hunter --- Changes for v5: - Split from platform series per Arnd's feedback Changes for v4: - New patch suggested by Adrian Hunter --- drivers/mmc/host/sdhci.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index ac7e11f37af7..dc5960e72a38 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -4193,6 +4193,12 @@ static void sdhci_allocate_bounce_buffer(struct sdhci_host *host) unsigned int bounce_size; int ret; + /* Drivers may have already allocated the buffer */ + if (host->bounce_buffer) { + bounce_size = host->bounce_buffer_size; + max_blocks = bounce_size / 512; + goto out; + } /* * Cap the bounce buffer at 64KB. Using a bigger bounce buffer * has diminishing returns, this is probably because SD/MMC @@ -4241,6 +4247,7 @@ static void sdhci_allocate_bounce_buffer(struct sdhci_host *host) host->bounce_buffer_size = bounce_size; +out: /* Lie about this since we're bouncing */ mmc->max_segs = max_blocks; mmc->max_seg_size = bounce_size; -- 2.43.0