Hi,
> >> > > Another approach to use PIO mode in opposite direction would
> >> > > increase
> >> the
> >> > > cpu loading and thus using system DMA is preferred workaround.
> >> > >
> >> > > Signed-off-by: Anand Gadiyar <gadiyar@xxxxxx>
> >> > > Signed-off-by: Ajay Kumar Gupta <ajay.gupta@xxxxxx>
> >> >
> >> > I think falling back to pio is better than this patch.
> >At the cost of cpu, which certainly is not preferred.
> >
> >>> It will most likely be only one transfer.
> >
> >How about host mode with multiple devices connected and doing
> >transfers?
> >Falling back to PIO would kill the cpu.
> >
> >>> Another approach is to allocate dma channels on a transfer basis.
> >
> >Can you elaborate this?
>
> It might be good idea to allocate the dma channels on tarnsfer basis as
> Felipe
> Suggested. The musb driver allocates dma channels for the first 8 enabled
> endpoints and higher endpoints works in PIO mode.
> For system dma if there are more nummber of Rx endpoints enabled but not
> used for data
> Transfer you might end up having many sdma channles allocated biut not
> used which will
> Impact in the system of not utilizing the sdma channels effectively.
Felipe, Is this what you meant? If so then I have a patch (copied below)
to fix this and I can post this one along with others.
-------------- cut here -----------------
Currently DMA channels are allocated and they remain allocated
even if there is no active data transfer. Added channel_release()
whenever there is no pending request.
Signed-off-by: Ajay Kumar Gupta <ajay.gupta@xxxxxx>
---
drivers/usb/musb/musb_gadget.c | 27 +++++++++++++++++++++------
drivers/usb/musb/musb_host.c | 14 ++++++++++++--
2 files changed, 33 insertions(+), 8 deletions(-)
diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
index fd842af..477a009 100644
--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -297,9 +297,13 @@ static void txstate(struct musb *musb, struct musb_request *req)
csr);
#ifndef CONFIG_MUSB_PIO_ONLY
- if (is_dma_capable() && musb_ep->dma) {
+
+ if (is_dma_capable() && musb->dma_controller) {
struct dma_controller *c = musb->dma_controller;
+ if (!musb_ep->dma)
+ musb_ep->dma = c->channel_alloc(c, musb_ep->hw_ep, 1);
+
use_dma = (request->dma != DMA_ADDR_INVALID);
/* MUSB_TXCSR_P_ISO is still set correctly */
@@ -433,6 +437,7 @@ void musb_g_tx(struct musb *musb, u8 epnum)
u8 __iomem *mbase = musb->mregs;
struct musb_ep *musb_ep = &musb->endpoints[epnum].ep_in;
void __iomem *epio = musb->endpoints[epnum].regs;
+ struct dma_controller *c = musb->dma_controller;
struct dma_channel *dma;
musb_ep_select(mbase, epnum);
@@ -535,6 +540,10 @@ void musb_g_tx(struct musb *musb, u8 epnum)
if (!request) {
DBG(4, "%s idle now\n",
musb_ep->end_point.name);
+ if (musb_ep->dma) {
+ c->channel_release(musb_ep->dma);
+ musb_ep->dma = NULL;
+ }
return;
}
}
@@ -585,6 +594,7 @@ static void rxstate(struct musb *musb, struct musb_request *req)
struct usb_request *request = &req->request;
struct musb_ep *musb_ep = &musb->endpoints[epnum].ep_out;
void __iomem *epio = musb->endpoints[epnum].regs;
+ struct dma_controller *c = musb->dma_controller;
unsigned fifo_count = 0;
u16 len = musb_ep->packet_sz;
u16 csr = musb_readw(epio, MUSB_RXCSR);
@@ -601,8 +611,10 @@ static void rxstate(struct musb *musb, struct musb_request *req)
return;
}
+ if (is_dma_capable() && musb->dma_controller && !musb_ep->dma)
+ musb_ep->dma = c->channel_alloc(c, musb_ep->hw_ep, 0);
+
if ((is_cppi_enabled() || is_cppi41_enabled()) && musb_ep->dma) {
- struct dma_controller *c = musb->dma_controller;
struct dma_channel *channel = musb_ep->dma;
/* NOTE: CPPI won't actually stop advancing the DMA
@@ -633,11 +645,9 @@ static void rxstate(struct musb *musb, struct musb_request *req)
if (request->actual < request->length) {
#ifdef CONFIG_USB_INVENTRA_DMA
if (is_dma_capable() && musb_ep->dma) {
- struct dma_controller *c;
struct dma_channel *channel;
int use_dma = 0;
- c = musb->dma_controller;
channel = musb_ep->dma;
/* We use DMA Req mode 0 in rx_csr, and DMA controller operates in
@@ -719,7 +729,6 @@ static void rxstate(struct musb *musb, struct musb_request *req)
#ifdef CONFIG_USB_TUSB_OMAP_DMA
if (tusb_dma_omap() && musb_ep->dma) {
- struct dma_controller *c = musb->dma_controller;
struct dma_channel *channel = musb_ep->dma;
u32 dma_addr = request->dma + request->actual;
int ret;
@@ -764,6 +773,7 @@ void musb_g_rx(struct musb *musb, u8 epnum)
void __iomem *mbase = musb->mregs;
struct musb_ep *musb_ep = &musb->endpoints[epnum].ep_out;
void __iomem *epio = musb->endpoints[epnum].regs;
+ struct dma_controller *c = musb->dma_controller;
struct dma_channel *dma;
musb_ep_select(mbase, epnum);
@@ -838,8 +848,13 @@ void musb_g_rx(struct musb *musb, u8 epnum)
musb_g_giveback(musb_ep, request, 0);
request = next_request(musb_ep);
- if (!request)
+ if (!request) {
+ if (musb_ep->dma) {
+ c->channel_release(musb_ep->dma);
+ musb_ep->dma = NULL;
+ }
return;
+ }
}
/* analyze request if the ep is hot */
diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index 89c8c35..001a1d6 100644
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -460,11 +460,21 @@ static void musb_advance_schedule(struct musb *musb, struct urb *urb,
*/
if (list_empty(&qh->hep->urb_list)) {
struct list_head *head;
+ struct dma_controller *dma = musb->dma_controller;
- if (is_in)
+ if (is_in) {
ep->rx_reinit = 1;
- else
+ if (ep->rx_channel) {
+ dma->channel_release(ep->rx_channel);
+ ep->rx_channel = NULL;
+ }
+ } else {
ep->tx_reinit = 1;
+ if (ep->tx_channel) {
+ dma->channel_release(ep->tx_channel);
+ ep->tx_channel = NULL;
+ }
+ }
/* Clobber old pointers to this qh */
musb_ep_set_qh(ep, is_in, NULL);
--
1.6.2.4
-----------------------------------------
-Ajay
>
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