On Thu, Feb 02, 2012 at 04:57:16AM +0000, Gupta, Ajay Kumar wrote: > Hi, > > On 31-01-2012 8:41, Gupta, Ajay Kumar wrote: > > > > >>> As a next step to dma-engine based cppi4.1 driver implementation > > >>> this RFC has the overview of changes in the musb driver. > > >>> RFC on CPPI slave driver changes will follow next. > > > > >>> Overview of changes in the musb driver > > >>> ====================================== > > > > >>> 1)Add a dma-engine.c file in the drivers/usb/musb folder > > >>> 2)This file will host the current musb dma APIs and translates them > > to > > >>> dmaengine APIs. > > >>> 3)This will help to keep the changes in drivers/usb/musb/musb* files > > >>> minimal and also to retain compatibility other DMA (Mentor etc.) > > >>> drivers which are yet to be moved to drivers/dma > > >>> 4)drivers/usb/musb/dma-engine.c, will wrap the dmaengine APIs to > > >>> make existing musb APIs compatible. > > >>> 5)drivers/usb/musb/dma-engine.c file will implement the filter > > >>> functions and also implement .dma_controller_create (allocates > > >>> & provides "dma_controller" object) and .dma_controller_delete > > >>> 6)CPPI4.1 DMA specific queue and buffer management will be internal > > >>> to slave CPPI DMA driver implementation. > > > > >> You mean drivers/dma/ driver? > > > > > yes. > > > > >> I think you are forgotting that CPPI 4.1 MUSB > > >> has some registers controlling DMA/interrupts beside those of CPPI > > 4.1 > > >> controller and MUSB core itself. How do they fit in your scheme? > > > > > We have been discussing on how to handle these in slave driver and > > > > These certainly cannot be handled in the slave driver because the > > registers are different for every controller implementation and, the > > main thing, they don't belong to CPPI 4.1 as such. > > Felipe suggested to use device tree for differences in register maps > among different platforms. > > I do see issues in reading wrapper interrupt status register and then > calling musb_interrupt() [defined inside musb_core.c] from slave driver. I have been thinking about that lately. In the end of the day, I want to remove direct dependencies between musb_core and glue. So what I was thinking about goes like so: Glue layer basically has to prepare musb->int_usb, musb->int_tx and musb->int_rx for musb. Maybe handle some glue specific stuff and so on, but the IRQ line still belongs to MUSB. So the idea would be to add something like: musb_platform_read_intrusb() musb_platform_read_intrtx() musb_platform_read_intrrx() those would default to basic: musb_readb(musb->mregs, MUSB_INTRUSB); musb_readw(musb->mregs, MUSB_INTRTX); musb_readw(musb->mregs, MUSB_INTRRX); if platform ops aren't passed. So, it would look something like: diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c index 72a424d..ba0bcc2 100644 --- a/drivers/usb/musb/musb_core.c +++ b/drivers/usb/musb/musb_core.c @@ -1488,9 +1488,9 @@ static irqreturn_t generic_interrupt(int irq, void *__hci) spin_lock_irqsave(&musb->lock, flags); - musb->int_usb = musb_readb(musb->mregs, MUSB_INTRUSB); - musb->int_tx = musb_readw(musb->mregs, MUSB_INTRTX); - musb->int_rx = musb_readw(musb->mregs, MUSB_INTRRX); + musb->int_usb = musb_platform_read_intusb(musb->controller); + musb->int_tx = musb_platform_read_inttx(musb->controller); + musb->int_rx = musb_platform_read_intrx(musb->controller); if (musb->int_usb || musb->int_tx || musb->int_rx) retval = musb_interrupt(musb); those would make sure to prepare the cached IRQ status registers for MUSB core. Keep in mind that this is only necessary because on DaVinci/OMAP-L13x/AM35x devices you guys have decided to make the wrapper read the IRQ status register from MUSB address space. And because those are clear-on-read, we're screwed. Oh well, this is the best I could come up with. Any problems you guys see ? -- balbi
Attachment:
signature.asc
Description: Digital signature
