Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756037AbeAHIo3 convert rfc822-to-8bit (ORCPT + 1 other); Mon, 8 Jan 2018 03:44:29 -0500 Received: from mailgw02.mediatek.com ([1.203.163.81]:53290 "EHLO mailgw02.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1755907AbeAHIoX (ORCPT ); Mon, 8 Jan 2018 03:44:23 -0500 X-Greylist: delayed 305 seconds by postgrey-1.27 at vger.kernel.org; Mon, 08 Jan 2018 03:44:21 EST X-UUID: 1f4973095b2645499547f312f2bd4f1d-20180108 Message-ID: <1515400735.21044.35.camel@mhfsdcap03> Subject: Re: FW: [PATCH v20 2/4] mailbox: mediatek: Add Mediatek CMDQ driver From: houlong wei To: Jassi Brar CC: Rob Herring , "; Matthias Brugger" , "; Daniel Kurtz" , "; Sascha Hauer" , "; Devicetree List" , "; Linux Kernel Mailing List" , "; linux-arm-kernel@lists.infradead.org; linux-mediatek@lists.infradead.org; srv_heupstream" , "; Sascha Hauer" , "; Philipp Zabel" , "; Nicolas Boichat" , "; CK Hu" , "; Cawa Cheng" , "; Bibby Hsieh" , "; YT Shen" , "; Daoyuan Huang" , "; Damon Chu" , "; Josh-YC Liu" , "; Glory Hung" , "; Jiaguang Zhang" , "; Dennis-YC Hsieh" , "; Monica Wang" , "; Houlong Wei" , "; Hs Liao" Date: Mon, 8 Jan 2018 16:38:55 +0800 In-Reply-To: <497f8e4ef7ae4c8a9b7b4ab259801306@mtkmbs01n1.mediatek.inc> References: <1483499169-16329-1-git-send-email-hs.liao@mediatek.com> <1483499169-16329-3-git-send-email-hs.liao@mediatek.com> <1485419833.990.1.camel@mtksdaap41> <1486359476.11424.33.camel@mtksdaap41> <1487733150.15869.11.camel@mtksdaap41> <1487854104.17813.1.camel@mtksdaap41> <497f8e4ef7ae4c8a9b7b4ab259801306@mtkmbs01n1.mediatek.inc> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-MTK: N Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: Hi Jassi, Sorry for reply so late. According to previous discussion, there are two methods to move dma_map_single() outside of spin_lock. (1) put in mtk-cmdq-helper.c, as described by HS on 2017-02-09. > I think a trade-off solution is to put in mtk-cmdq-helper.c. > Although it is a mailbox client, it is not a CMDQ client. > We can include mailbox_controller.h in mtk-cmdq-helper.c (instead of mtk-cmdq.h), and then map dma at cmdq_pkt_flush_async before mbox_send_message. > pkt->pa_base = dma_map_single(client->chan->mbox->dev, pkt->va_base, > pkt->cmd_buf_size, DMA_TO_DEVICE); (2) schedule a tasklet in send_data(). After internal discussion with HS and other experts, now we prefer method (1). How do you think about it? Thanks Houlong > -----Original Message----- > From: Horng-Shyang Liao [mailto:hs.liao@mediatek.com] > Sent: Thursday, February 23, 2017 8:48 PM > To: Jassi Brar > Cc: Rob Herring ; Matthias Brugger ; Daniel Kurtz ; Sascha Hauer ; Devicetree List ; Linux Kernel Mailing List ; linux-arm-kernel@lists.infradead.org; linux-mediatek@lists.infradead.org; srv_heupstream ; Sascha Hauer ; Philipp Zabel ; Nicolas Boichat ; CK Hu (胡俊光) ; Cawa Cheng (鄭曄禧) ; Bibby Hsieh (謝濟遠) ; YT Shen (沈岳霆) ; Daoyuan Huang (黃道原) ; Damon Chu (朱峻賢) ; Josh-YC Liu (劉育誠) ; Glory Hung (洪智瑋) ; Jiaguang Zhang (张加广) ; Dennis-YC Hsieh (謝宇哲) ; Monica Wang (王孟婷) ; Houlong Wei (魏厚龙) ; Hs Liao (廖宏祥) > Subject: Re: [PATCH v20 2/4] mailbox: mediatek: Add Mediatek CMDQ driver > > On Thu, 2017-02-23 at 09:40 +0530, Jassi Brar wrote: > > On Wed, Feb 22, 2017 at 8:42 AM, Horng-Shyang Liao wrote: > > > On Thu, 2017-02-16 at 21:02 +0530, Jassi Brar wrote: > > >> On Mon, Feb 6, 2017 at 11:07 AM, Horng-Shyang Liao wrote: > > >> > Hi Jassi, > > >> > > > >> > On Wed, 2017-02-01 at 10:52 +0530, Jassi Brar wrote: > > >> >> On Thu, Jan 26, 2017 at 2:07 PM, Horng-Shyang Liao wrote: > > >> >> > Hi Jassi, > > >> >> > > > >> >> > On Thu, 2017-01-26 at 10:08 +0530, Jassi Brar wrote: > > >> >> >> On Wed, Jan 4, 2017 at 8:36 AM, HS Liao wrote: > > >> >> >> > > >> >> >> > diff --git a/drivers/mailbox/mtk-cmdq-mailbox.c > > >> >> >> > b/drivers/mailbox/mtk-cmdq-mailbox.c > > >> >> >> > new file mode 100644 > > >> >> >> > index 0000000..747bcd3 > > >> >> >> > --- /dev/null > > >> >> >> > +++ b/drivers/mailbox/mtk-cmdq-mailbox.c > > >> >> >> > > >> >> >> ... > > >> >> >> > > >> >> >> > +static void cmdq_task_exec(struct cmdq_pkt *pkt, struct > > >> >> >> > +cmdq_thread *thread) { > > >> >> >> > + struct cmdq *cmdq; > > >> >> >> > + struct cmdq_task *task; > > >> >> >> > + unsigned long curr_pa, end_pa; > > >> >> >> > + > > >> >> >> > + cmdq = dev_get_drvdata(thread->chan->mbox->dev); > > >> >> >> > + > > >> >> >> > + /* Client should not flush new tasks if suspended. */ > > >> >> >> > + WARN_ON(cmdq->suspended); > > >> >> >> > + > > >> >> >> > + task = kzalloc(sizeof(*task), GFP_ATOMIC); > > >> >> >> > + task->cmdq = cmdq; > > >> >> >> > + INIT_LIST_HEAD(&task->list_entry); > > >> >> >> > + task->pa_base = dma_map_single(cmdq->mbox.dev, pkt->va_base, > > >> >> >> > + pkt->cmd_buf_size, > > >> >> >> > + DMA_TO_DEVICE); > > >> >> >> > > > >> >> >> You seem to parse the requests and responses, that should > > >> >> >> ideally be done in client driver. > > >> >> >> Also, we are here in atomic context, can you move it in > > >> >> >> client driver (before the spin_lock)? > > >> >> >> Maybe by adding a new 'pa_base' member as well in 'cmdq_pkt'. > > >> >> > > > >> >> > will do > > >> > > > >> > I agree with moving dma_map_single out from spin_lock. > > >> > > > >> > However, mailbox clients cannot map virtual memory to mailbox > > >> > controller's device for DMA. > > >> > > > >> If DMA is a resource used by MBox to transfer data, then yes the > > >> mapping needs to be done in the Mbox controller driver. To map > > >> memory outside of spinlock, you could schedule a tasklet in send_data() ? > > > > > > Hi Jassi, > > > > > > For CMDQ, the order of CMDQ tasks should be guaranteed. > > > However, it seems tasklet cannot ensure this requirement. > > > > > > Quote from Linux Device Drivers 3rd edition ch7. > > > "void tasklet_schedule(struct tasklet_struct *t); > > > Schedule the tasklet for execution. If a tasklet is scheduled > > > again before it has a chance to run, it runs only once...." > > > > > Not sure what bothers you. > > If you only add requests to a list, protected by some spinlock, during > > send_datam you could always iterate over (submit) requests in the > > order you queued them. > > Hi Jassi, > > OK. I will do it. > > Thanks, > HS > > >