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Date: Thu, 18 Jan 2018 12:30:20 +0800
From: houlong wei <houlong.wei@...iatek.com>
To: Jassi Brar <jassisinghbrar@...il.com>
CC: Rob Herring <robh+dt@...nel.org>,
"; Matthias Brugger" <matthias.bgg@...il.com>,
"; Daniel Kurtz" <djkurtz@...omium.org>,
"; Sascha Hauer" <s.hauer@...gutronix.de>,
"; Devicetree List" <devicetree@...r.kernel.org>,
"; Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
"; linux-arm-kernel@...ts.infradead.org;
linux-mediatek@...ts.infradead.org; srv_heupstream"
<srv_heupstream@...iatek.com>,
"; Sascha Hauer" <kernel@...gutronix.de>,
"; Philipp Zabel" <p.zabel@...gutronix.de>,
"; Nicolas Boichat" <drinkcat@...omium.org>,
"; CK Hu (胡俊光)"
<ck.hu@...iatek.com>,
"; Cawa Cheng (鄭曄禧)"
<cawa.cheng@...iatek.com>,
"; Bibby Hsieh (謝濟遠)"
<Bibby.Hsieh@...iatek.com>,
"; YT Shen (沈岳霆)"
<yt.shen@...iatek.com>,
"; Daoyuan Huang (黃道原)"
<Daoyuan.Huang@...iatek.com>,
"; Damon Chu (朱峻賢)"
<damon.chu@...iatek.com>,
"; Josh-YC Liu (劉育誠)"
<Josh-YC.Liu@...iatek.com>,
"; Glory Hung (洪智瑋)"
<glory.hung@...iatek.com>,
"; Jiaguang Zhang (张加广)"
<Jiaguang.Zhang@...iatek.com>,
"; Dennis-YC Hsieh (謝宇哲)"
<Dennis-YC.Hsieh@...iatek.com>,
"; Monica Wang (王孟婷)"
<monica.wang@...iatek.com>,
"; Houlong Wei (魏厚龙)"
<houlong.wei@...iatek.com>,
"; Hs Liao (廖宏祥)"
<hs.liao@...iatek.com>
Subject: Re: FW: [PATCH v20 2/4] mailbox: mediatek: Add Mediatek CMDQ driver
Sorry to send the mail again because I missed some mail lists by
mistake.
Hi Jassi,
We prefer to use method (1) to move dma_map_single() outside of
spin_lock. Do you have any comment about this?
Thanks,
Houlong
On Mon, 2018-01-08 at 16:38 +0800, houlong wei wrote:
> 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@...iatek.com]
> > Sent: Thursday, February 23, 2017 8:48 PM
> > To: Jassi Brar <jassisinghbrar@...il.com>
> > Cc: Rob Herring <robh+dt@...nel.org>; Matthias Brugger <matthias.bgg@...il.com>; Daniel Kurtz <djkurtz@...omium.org>; Sascha Hauer <s.hauer@...gutronix.de>; Devicetree List <devicetree@...r.kernel.org>; Linux Kernel Mailing List <linux-kernel@...r.kernel.org>; linux-arm-kernel@...ts.infradead.org; linux-mediatek@...ts.infradead.org; srv_heupstream <srv_heupstream@...iatek.com>; Sascha Hauer <kernel@...gutronix.de>; Philipp Zabel <p.zabel@...gutronix.de>; Nicolas Boichat <drinkcat@...omium.org>; CK Hu (胡俊光) <ck.hu@...iatek.com>; Cawa Cheng (鄭曄禧) <cawa.cheng@...iatek.com>; Bibby Hsieh (謝濟遠) <Bibby.Hsieh@...iatek.com>; YT Shen (沈岳霆) <yt.shen@...iatek.com>; Daoyuan Huang (黃道原) <Daoyuan.Huang@...iatek.com>; Damon Chu (朱峻賢) <damon.chu@...iatek.com>; Josh-YC Liu (劉育誠) <Josh-YC.Liu@...iatek.com>; Glory Hung (洪智瑋) <glory.hung@...iatek.com>; Jiaguang Zhang (张加广) <Jiaguang.Zhang@...iatek.com>; Dennis-YC Hsieh (謝宇哲) <Dennis-YC.Hsieh@...iatek.com>; Monica Wang (王孟婷) <monica.wang@...iatek.com>; Houlong Wei (魏厚龙) <houlong.wei@...iatek.com>; Hs Liao (廖宏祥) <hs.liao@...iatek.com>
> > 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 <hs.liao@...iatek.com> 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 <hs.liao@...iatek.com> 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 <hs.liao@...iatek.com> 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 <hs.liao@...iatek.com> 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
> >
> >
> >
>
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