> -----Original Message----- > From: svenkatr@xxxxxxxxx [mailto:svenkatr@xxxxxxxxx] On Behalf Of Venkatraman S > Sent: Wednesday, May 05, 2010 9:56 PM > To: Shilimkar, Santosh > Cc: linux-omap@xxxxxxxxxxxxxxx; linux-mmc@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > Chikkature Rajashekar, Madhusudhan; Adrian Hunter; Tony Lindgren > Subject: Re: [PATCH v8 1/2] sDMA: descriptor autoloading feature > > On Wed, May 5, 2010 at 5:31 PM, Shilimkar, Santosh > <santosh.shilimkar@xxxxxx> wrote: > > > > > >> -----Original Message----- > >> From: svenkatr@xxxxxxxxx [mailto:svenkatr@xxxxxxxxx] On Behalf Of Venkatraman S > >> Sent: Wednesday, May 05, 2010 5:20 PM > >> To: Shilimkar, Santosh > >> Cc: linux-omap@xxxxxxxxxxxxxxx; linux-mmc@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > >> Chikkature Rajashekar, Madhusudhan; Adrian Hunter; Tony Lindgren > >> Subject: Re: [PATCH v8 1/2] sDMA: descriptor autoloading feature > >> > >> [Long sections have been trimmed to the context of the discussion] > >> On Wed, May 5, 2010 at 3:02 PM, Shilimkar, Santosh > >> <santosh.shilimkar@xxxxxx> wrote: > >> >> -----Original Message----- > >> >> +static int dma_sglist_set_phy_params(struct omap_dma_sglist_node *sghead, > >> >> + dma_addr_t phyaddr, int nelem) > >> >> +{ > >> >> + struct omap_dma_sglist_node *sgcurr, *sgprev; > >> >> + dma_addr_t elem_paddr = phyaddr; > >> >> + > >> >> + for (sgprev = sghead; > >> >> + sgprev < sghead + nelem; > >> >> + sgprev++) { > >> >> + > >> >> + sgcurr = sgprev + 1; > >> >> + sgprev->next = sgcurr; > >> >> + elem_paddr += (int)sizeof(*sgcurr); > >> >> + sgprev->next_desc_add_ptr = elem_paddr; > >> >> + > >> >> + switch (sgcurr->desc_type) { > >> >> + case OMAP_DMA_SGLIST_DESCRIPTOR_TYPE1: > >> >> + omap_dma_list_set_ntype(sgprev, 1); > >> >> + break; > >> >> + > >> >> + case OMAP_DMA_SGLIST_DESCRIPTOR_TYPE2a: > >> >> + /* intentional no break */ > >> >> + case OMAP_DMA_SGLIST_DESCRIPTOR_TYPE2b: > >> >> + omap_dma_list_set_ntype(sgprev, 2); > >> >> + break; > >> >> + > >> >> + case OMAP_DMA_SGLIST_DESCRIPTOR_TYPE3a: > >> >> + /* intentional no break */ > >> >> + case OMAP_DMA_SGLIST_DESCRIPTOR_TYPE3b: > >> >> + omap_dma_list_set_ntype(sgprev, 3); > >> >> + break; > >> >> + > >> >> + default: > >> >> + return -EINVAL; > >> >> + > >> >> + } > >> > Are we supporting all the descriptor types. I think only type2a is > >> > supported. In that case please add FIXME, or WARN message here. > >> > >> From DMA perspective, all are supported - no restrictions. Only I have > >> not figured > >> out how to use type 2b and type 3b descriptors. It's not the fault of > >> DMA driver or > >> specification :-) It's actually upto the client to select the right type. > > OK. Then the question which I wanted to ask. > > For TX, 2b should have been better choice than 2a isn't it? > > Not much of a difference (as the space allocation is common), but I > couldn't get 2b working correctly. > Will try that once I get some clarification from hardware team. Add a FIXME then with description in the code so that it's not forgotten once the code is merged. > > >> > >> >> + > >> >> + lcfg->sghead = sgparams; > >> >> + lcfg->num_elem = nelem; > >> >> + lcfg->sgheadphy = padd; > >> >> + lcfg->pausenode = -1; > >> >> + > >> >> + > >> >> + if (NULL == chparams) > >> > Minute point really. Better readability "ch_params" > >> OK -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
