From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 264343EDE5D; Tue, 12 May 2026 18:03:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778609036; cv=none; b=AbhaRfm5gRTr6sgQXwnqM1IpY8vsfP731+3MFOQLeRxqDp7gJniYCNJn8W7TnjVa3UhuAzt5n4c5pKdWq256MLiAZsY77Qr2ZmKDjL5V0k4IkSzcXInCu3qgSKJSF8/u6nFtvRKjFlNhx6znIt7x6RjS+GZcY1VsRQQjwosBC4w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778609036; c=relaxed/simple; bh=4X0lANsi8ek67RnIQCFecdNJRDMwt8Ufs6pWHZ1Qugw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TiopVc9d+5r61st/SxsDMps9wTt/45PLP8UJUoh+HcS1zymX7wdSAHe3MsIGihe+rmgkLIlD7UNWY9JowZHS5P2KvCf99Qr0wyrcex/6BQMcDccMKYLsRxabwiTsN2SM2caWkw5lvjMT29O0xadB4AvhKq2jHPiZMqN88e4o7Gs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=n22v9TTf; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="n22v9TTf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B2BBFC2BCB0; Tue, 12 May 2026 18:03:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778609036; bh=4X0lANsi8ek67RnIQCFecdNJRDMwt8Ufs6pWHZ1Qugw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=n22v9TTfa/Wddh8vqRKu3pSJJ3Hkq15D69q7063OCEmqIoBeiOlOAw8EKNCj87ZPb GIVysW6qL2+Knz17owpYa8WClwWPcxXeLTIAnnBRubWgG5gyTLW1KCsRZs9D2pjiqf 8ANJvADyZd+9NOJ/AXWEUwW8TBpE5L7qywbGifgA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Aaro Koskinen Subject: [PATCH 7.0 041/307] USB: omap_udc: DMA: Dont enable burst 4 mode Date: Tue, 12 May 2026 19:37:16 +0200 Message-ID: <20260512173940.991599636@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260512173940.117428952@linuxfoundation.org> References: <20260512173940.117428952@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Aaro Koskinen commit 3f91484f6c13c434bd573ca6b6779c26adb0ddab upstream. Commit 65111084c63d7 ("USB: more omap_udc updates (dma and omap1710)") added setting for DMA burst 4 mode. But I think this should be undone for two reasons: - It breaks DMA on 15xx boards - transfers just silently stall. - On newer OMAP1 boards, like Nokia 770 (omap1710), there is no measurable performance impact when testing TCP throughput with g_ether with large 15000 byte MTU size. It's also worth noting that when the original change was made, the OMAP_DMA_DATA_BURST_4 handling in arch/arm/plat-omap/dma.c was broken, and actually resulted in the same as the OMAP_DMA_DATA_BURST_DIS i.e. burst disabled. This was fixed not until a couple kernel releases later in an unrelated commit 1a8bfa1eb998a ("[ARM] 3142/1: OMAP 2/5: Update files common to omap1 and omap2"). So based on this it seems there was never really a very good reason to enable this burst mode in omap_udc, so remove it now to allow 15xx DMA to work again (it provides 2x throughput compared to PIO mode). Fixes: 65111084c63d ("[PATCH] USB: more omap_udc updates (dma and omap1710)") Cc: stable Signed-off-by: Aaro Koskinen Link: https://patch.msgid.link/ad06qHLclWHeSGnV@darkstar.musicnaut.iki.fi Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/udc/omap_udc.c | 4 ---- 1 file changed, 4 deletions(-) --- a/drivers/usb/gadget/udc/omap_udc.c +++ b/drivers/usb/gadget/udc/omap_udc.c @@ -733,8 +733,6 @@ static void dma_channel_claim(struct oma if (status == 0) { omap_writew(reg, UDC_TXDMA_CFG); /* EMIFF or SDRC */ - omap_set_dma_src_burst_mode(ep->lch, - OMAP_DMA_DATA_BURST_4); omap_set_dma_src_data_pack(ep->lch, 1); /* TIPB */ omap_set_dma_dest_params(ep->lch, @@ -756,8 +754,6 @@ static void dma_channel_claim(struct oma UDC_DATA_DMA, 0, 0); /* EMIFF or SDRC */ - omap_set_dma_dest_burst_mode(ep->lch, - OMAP_DMA_DATA_BURST_4); omap_set_dma_dest_data_pack(ep->lch, 1); } }