On Thu, Feb 02, 2012 at 03:12:44PM +0400, Sergei Shtylyov wrote: > Hello. > > On 02-02-2012 13:09, Felipe Balbi 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 ? > > On DaVinci/OMAP-L1x these 3 calls need to extract data from a > single 32-bit register, so that doesn't seem a good idea to me. The that's a problem on DaVinci/OMAP-L1x. > current scheme seems OK to me. Or either implement a signle function > to read all 3 interrupt masks... > > musb_platform_read_ints() I wanted to avoid glue layer having to access the musb pointer directly. If I implement musb_platform_read_ints() I will have to pass musb as argument, or agree on another way to return the values. Thanks, but no thanks. I want to remove direct access of musb from glue layer, and at some point I will have to do it in order to fix a few problems we might still have with modules, basically because glue layer could be trying to access memory which was freed already. -- balbi
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