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:[email protected]] > Sent: Thursday, February 23, 2017 8:48 PM > To: Jassi Brar <[email protected]> > Cc: Rob Herring <[email protected]>; Matthias Brugger > <[email protected]>; Daniel Kurtz <[email protected]>; Sascha Hauer > <[email protected]>; Devicetree List <[email protected]>; Linux > Kernel Mailing List <[email protected]>; > [email protected]; [email protected]; > srv_heupstream <[email protected]>; Sascha Hauer > <[email protected]>; Philipp Zabel <[email protected]>; Nicolas > Boichat <[email protected]>; CK Hu (胡俊光) <[email protected]>; Cawa Cheng > (鄭曄禧) <[email protected]>; Bibby Hsieh (謝濟遠) > <[email protected]>; YT Shen (沈岳霆) <[email protected]>; Daoyuan > Huang (黃道原) <[email protected]>; Damon Chu (朱峻賢) > <[email protected]>; Josh-YC Liu (劉育誠) <[email protected]>; Glory > Hung (洪智瑋) <[email protected]>; Jiaguang Zhang (张加广) > <[email protected]>; Dennis-YC Hsieh (謝宇哲) > <[email protected]>; Monica Wang (王孟婷) <[email protected]>; > Houlong Wei (魏厚龙) <[email protected]>; Hs Liao (廖宏祥) > <[email protected]> > 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 <[email protected]> > > 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 > > >> <[email protected]> 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 > > >> >> <[email protected]> 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 <[email protected]> > > >> >> >> 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 > > >
