From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.221.44 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793125733; b=RcRZ6AWpM18HAqtobQDyDQpb/wtmbso55LpYB0nbfXkLlEgvHStBfZpPwaEx7swwXzYY PtD1fV466n46KJNCnba5WXh2haZCkSLr0pJWv8P09msOUTnSUTYPNCoJNBw5DQMAN72ms X57c00FBd+kBZ7yoex57s4UzZBllJP0P8x+Qur+y7TBsVGT6ngfDEybf+f29UoJev8sSs WSq6Z6+9YMTKRuf1CtgtxJ+UavLxekjItKDfd3fpzAf202D8WNs3+iXrJCTG4Xh0LjyuD eRO5ZLg9HDRnezCkOuqnlo5KGW0blxIZISiQqWhlCZcZ/FelNJrP/Oo7yuwrixOxM5g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793125733; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: Message-ID:Date:MIME-Version:User-Agent:Subject:To:Cc:References: Content-Language:From:In-Reply-To:Content-Type: Content-Transfer-Encoding; bh=BLfFNn1Qcpgkc/CE+gfkXeaI8Qpi2GlNUfZr/MSyrCY=; b=xYHQ/pC2barUD5QgX0ZZu7DRhjkIxlqCFbgdrJ4LyyMWqu/Ig8XgNpQDx2teOUgPbQX5 V1aoNdEzyGzLFxXOvQL1RGZuW4PfS8cDl8P6T6iDIgGu+it6/LdnmRvuhX1BR6PrgV8U1 NbskDTLkUxQltvfZUzdguqClKAhG5gGVhTAVH3hoo6xAjWlo79AX9ZheNAj2uAVFShls4 vowL4n2yl0pF82/8gnTIy4WbN5j2Co4qj5SKzxsKM9fc58F5bR7zCVnuurH33MblHm3FW KGfkBymN4NJZ+NJmo5RI7u/8dInkPb9ISwIAkwK5V5J+hVWhWq7GhHMzo1WcJt46p0Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b="IzuVmn/3"; arc=none smtp.remote-ip=209.85.221.44 Received: from mail-wr1-f44.google.com (mail-wr1-f44.google.com [209.85.221.44]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 57D53606A322 for ; Tue, 27 Oct 2026 18:28:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 57D53606A322 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=IzuVmn/3 Received: by mail-wr1-f44.google.com with SMTP id ffacd0b85a97d-48dfc0421d9so137424f8f.1 for ; Tue, 27 Oct 2026 11:28:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1793125732; x=1793730532; darn=vger.kernel.org; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to :content-type; bh=BLfFNn1Qcpgkc/CE+gfkXeaI8Qpi2GlNUfZr/MSyrCY=; b=IzuVmn/3PK9k7xpmQcANtQTaHfMbFHFVZuCQQjBOZcwHtm9l0fcAnfhVtYYXkWluIT w71AMui723QvIQqh5zjvS+Np2nRcHflIOKTGYdUNpV8vgv4xEyY506P7MQj6e72izXZ0 i+E5hp1Yq6Lwl3WJ+WJ/9yIPFzgAp//w5FFtv3M0Jr4WdLpaIV78oN2QGHTbDB4dbbXu qjMgzh+W/tRdSMASwKyRnLFWP7gG7UXgblH8hluuvE8pzPnzU5Oa59G79Yg6Qdso0yig hvMsDOzfkUrikadI+u/5jNAghab5Umy3QgQxkFXyurFUkaAPLFfxgmSq9DLmKqkawzUN aBYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793125732; x=1793730532; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=BLfFNn1Qcpgkc/CE+gfkXeaI8Qpi2GlNUfZr/MSyrCY=; b=LzdITWQJWlyql1HGAcbtC51mM/ye9G1A6QQR3HdeEfzJ4dnJJg91oEkBYWTHbrMs7f QW8ixYpooSCpfW/p9uDOE9jlAWTKovJ8k4HXK03WxC5OzsttrfFFFyQNPS44uuus921Z /G1HA1D7yeSmjKfDCbdQbxH/m4wvPB1/sV+BWLEwxA2YXi9swZTL+O4bw35u6crYh8Ha bW1g688ael9ykpBwtQMMHGLHsDs/7M1rPtqUz/VMXuZsGhtJjWGjU0t7oQ03yqFLGL8o S+tSNZuzRRzej6wMDOLaKb5bOGX5Au2m9SZsmaMBkbOfwPqOAhLs8OGJvHP/M1W8g6aT HgIg== X-Forwarded-Encrypted: i=1; AKwUvBwN/7gBYEVAH4G1HNQdpx1Yh+OBKlwlXXj8pO8h9idhHSQLyRMtFNhufHoF/hLKlIQlN8yUh8vl0HjKhnk=@vger.kernel.org X-Gm-Message-State: AFq9FYK12OWCk3DfgF5NfiP/HrEhHXKFMAmheHLjGbNWu4GYIrvSusIk AT992/pYytpBnDVUCOJOzcJKkdAw8nYGH6lfx7quQdcHDwWEIP25ZxpS X-Gm-Gg: AYBFou2xOjRw10DfjbsoC5/QBUrsrCl9EEZQmmf5d3vDzCB38TkdXsGYNciZzY/rcHY e2Ie+m34OTvMc8OOpCcJ8HA9TOLeuCU29PleIVXDpflZwLE/Cpddf0O05IKqYNUCbHCinjkq82l IJ7jFEouHCPTDN5SM9ZgKqjAPRC1TzXaDaMg+TtPLJ/FENjydhiHZzGCXQ7SAqU2ROIAnSqsLqL 7CQIUFVhNafd75wBUvt54W+oy6h2PvKF+Q98jE1REJN+quz9Uj22JLd8tQaNbP3XS2NUOVKHaau 7TzNgMNdbk0E95xj26MibxEaTaDQIK3JDuCM2o78cxDCfm5StZs+2yit3BOEnSk5HzEGlHQnWF1 kVV2OxIdEhrdSPKMLSwatvCKIJ37Q9T+U1xGoVZsMCNIYcxowGxR+2ycCZHzoORUCkGkqqxq4HE US+wrwPP2mKVcIsu65YEp5u1VH+sULroKF/+SlU+jYdthy6/Keg2L9NYtkUmobZPiWl+MCYMgZY 0Qc2E2JTAsjBmlzMFR84Gje6OA7bhhhp/65TxoxIS3Zf3YvbWMS5s1bWo9GZuZGdilcdQPljKbc p7HcID7hyxhh/h1AxVT+/erL1HHirlAaZxpW+ntk48ksXWqzPJG3DLhbABhLV+pPkmw= X-Received: by 2002:a05:6000:26cc:b0:48d:ef0e:b791 with SMTP id ffacd0b85a97d-48e5d313b51mr689662f8f.54.1793125731380; Tue, 27 Oct 2026 11:28:51 -0700 (PDT) Received: from [192.168.42.93] (193-154-207-67.adsl.highway.telekom.at. [193.154.207.67]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e3ecd3555sm23765915f8f.42.2026.10.27.11.28.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 27 Oct 2026 11:28:50 -0700 (PDT) Message-ID: <60d0962f-8769-49e8-9674-48ec98278529@gmail.com> Date: Tue, 27 Oct 2026 19:28:49 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] dmaengine: pl08x: mark slave channels as DMA_PRIVATE To: Frank Li Cc: vkoul@kernel.org, Frank.Li@kernel.org, dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org References: <20261027070037.1809112-1-andi.platschek@gmail.com> Content-Language: en-US From: Andreas Gabriel-Platschek In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 10/27/26 3:39 PM, Frank Li wrote: > On Tue, Oct 27, 2026 at 08:00:37AM +0100, Andreas Gabriel-Platschek wrote: >> [You don't often get email from andi.platschek@gmail.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] >> >> The pl08x slave engine channels are only ever handed out through >> explicit requests: DT clients go via pl08x_of_xlate() and the >> platform-data path uses dma_request_channel() with a filter, both of >> which end up in dma_get_slave_channel(). They are not meant to be >> published in the general-purpose channel table. >> >> Mark the slave device with DMA_PRIVATE at probe time so the dmaengine >> core treats it as always-private. Without this, if a dmaengine client >> is already active when the device is registered, >> dma_async_device_register() takes a reference on every channel, > Code change is okay. Are you sure the above description correct? where > code set it active when dma_async_device_register(). > > Frank I do think so, because async_damengine_get() -> dmaengine_get() is called from crypto/async_tx/async_tx.c and increments the dmaengine_ref_count. This way the dmaengine_ref_count is already >=1 before the pl08x dmaengine probes. dma_async_device_register() (in dmaengine.c) iterates over the channels inside of the following conditional:  if (dmaengine_ref_count && !dma_has_cap(DMA_PRIVATE, device->cap_mask)) and in there a dma_chan_get() is called for each channel and increments the client_count. With a client_count  >=1 we fail once pl08x_of_xlate()->dma_get_slave_channel() is called. setting DMA_PRIVATE prevents the client_count from being incremented by the core, keeping the client_count at 0 until a real client requests one hope that makes sense? best! Andi > >> and >> the subsequent dma_get_slave_channel() from pl08x_of_xlate() fails >> because the channel is no longer free (client_count != 0), leaving DT >> slave clients unable to acquire channels. >> >> The memcpy engine stays public as it is intended to be shared through >> the per-CPU channel table. >> >> Signed-off-by: Andreas Gabriel-Platschek >> --- >> drivers/dma/amba-pl08x.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c >> index 543c2eb8cfa8..06881d3f29a9 100644 >> --- a/drivers/dma/amba-pl08x.c >> +++ b/drivers/dma/amba-pl08x.c >> @@ -2775,6 +2775,7 @@ static int pl08x_probe(struct amba_device *adev, const struct amba_id *id) >> pl08x->has_slave = true; >> dma_cap_set(DMA_SLAVE, pl08x->slave.cap_mask); >> dma_cap_set(DMA_CYCLIC, pl08x->slave.cap_mask); >> + dma_cap_set(DMA_PRIVATE, pl08x->slave.cap_mask); >> pl08x->slave.dev = &adev->dev; >> pl08x->slave.device_free_chan_resources = >> pl08x_free_chan_resources; >> -- >> 2.47.3 >>