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@xxxxxxxxxxxx] > Sent: Thursday, February 23, 2017 8:48 PM > To: Jassi Brar <jassisinghbrar@xxxxxxxxx> > Cc: Rob Herring <robh+dt@xxxxxxxxxx>; Matthias Brugger <matthias.bgg@xxxxxxxxx>; Daniel Kurtz <djkurtz@xxxxxxxxxxxx>; Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>; Devicetree List <devicetree@xxxxxxxxxxxxxxx>; Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-mediatek@xxxxxxxxxxxxxxxxxxx; srv_heupstream <srv_heupstream@xxxxxxxxxxxx>; Sascha Hauer <kernel@xxxxxxxxxxxxxx>; Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>; Nicolas Boichat <drinkcat@xxxxxxxxxxxx>; CK Hu (胡俊光) <ck.hu@xxxxxxxxxxxx>; Cawa Cheng (鄭曄禧) <cawa.cheng@xxxxxxxxxxxx>; Bibby Hsieh (謝濟遠) <Bibby.Hsieh@xxxxxxxxxxxx>; YT Shen (沈岳霆) <yt.shen@xxxxxxxxxxxx>; Daoyuan Huang (黃道原) <Daoyuan.Huang@xxxxxxxxxxxx>; Damon Chu (朱峻賢) <damon.chu@xxxxxxxxxxxx>; Josh-YC Liu (劉育誠) <Josh-YC.Liu@xxxxxxxxxxxx>; Glory Hung (洪智瑋) <glory.hung@xxxxxxxxxxxx>; Jiaguang Zhang (张加广) <Jiaguang.Zhang@xxxxxxxxxxxx>; Dennis-YC Hsieh (謝宇哲) <Dennis-YC.Hsieh@xxxxxxxxxxxx>; Monica Wang (王孟婷) <monica.wang@xxxxxxxxxxxx>; Houlong Wei (魏厚龙) <houlong.wei@xxxxxxxxxxxx>; Hs Liao (廖宏祥) <hs.liao@xxxxxxxxxxxx> > 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@xxxxxxxxxxxx> 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@xxxxxxxxxxxx> 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@xxxxxxxxxxxx> 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@xxxxxxxxxxxx> 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 > > > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
