> -----Original Message----- > From: Vinod Koul [mailto:vinod.koul@xxxxxxxxx] > Sent: Wednesday, January 24, 2018 6:41 AM > To: Hyun Kwon <hyunk@xxxxxxxxxx> > Cc: dmaengine@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; Michal Simek > <michal.simek@xxxxxxxxxx>; Tejas Upadhyay <TEJASU@xxxxxxxxxx> > Subject: Re: [PATCH 2/2] dma: xilinx: dpdma: Add the Xilinx DisplayPort > DMA engine driver > > On Tue, Jan 23, 2018 at 05:03:19PM +0000, Hyun Kwon wrote: > > > > why should this be a compile option > > > > > > > This debugfs code is for testing / regression, and we don't want to enable > it > > for regular users. > > Right and that is why you have CONFIG_DEBUGFS, why not use that? > > > > do you need all these headers? > > > > > > > I directly included all headers that are used in this driver. Some of them > can > > be removed from indirect inclusions, and I'm fine with that. Please let me > know > > if that's your preference. > > Yes pls remove the ones that are needed > > > > > +#define XILINX_DPDMA_INTR_DESC_DONE_SHIFT 0 > > > > > > you can define a common shift using ffs > > > > > > > I guess you mean to replace, (value & MASK) << SHIFT, with > > (value & MASK) << ffs(MASK). I'll change to that way. Let me know > otherwise. > > yes and you may use the ones in bitfield.h > > > > what does it mean (lower 32 bit of Nth 4KB page) > > > > > > > Each descriptor can point up to 5 - 48bit address payloads. src_addr* > fields > > contain lower 32bit of 48bit address. Remaining upper 16bit is > programmed in > > addr_ext* fields. > > pls document this > > > > > +static int xilinx_dpdma_config(struct dma_chan *dchan, > > > > + struct dma_slave_config *config) > > > > +{ > > > > + if (config->direction != DMA_MEM_TO_DEV) > > > > + return -EINVAL; > > > > > > ?? Why are the config values not used, how else do you configure the > > > channel? > > > > > > > There's not much configuration to be done. Channels are pretty much > identical > > with fixed configurations. > > hmmm, you do support DMA_SLAVE right? > Yes, and it's single direction, DMA_MEM_TO_DEV. > > > why have these wrappers which do not do anything? > > > > > > > It's just my personal preference to split into different code partitions, and > > each section is partitioned / grouped with some comment line. :-) > > Ex, a partition for struct dma_chan, and another one for > > struct xilinx_dpdma_chan. It gives me sort of abstracted view. But it may > be > > just me, and it comes with extra indirections. I'll remove unnecessary > wrappers. > > wrapper without any logic dont help > > > > > + for (i = 0; i < XILINX_DPDMA_NUM_CHAN; i++) > > > > + if (xdev->chan[i]) > > > > + xilinx_dpdma_chan_remove(xdev->chan[i]); > > > > > > At this point your irq is still enabled and can fire, and can schedule > > > tasklet.. Are you sure you are okay with that? > > > > > > > Ok. You mean that an interrupt can occur right before > > xilinx_dpdma_disable_intr(), and the interrupt may be handled in the > middle or > > after removing this driver. I'll switch to request_irq() from > > devm_request_irq(), and remove the irq when removing the driver. > > yes and ensure tasklets are quiesced > > > > > +MODULE_AUTHOR("Xilinx, Inc."); > > > > +MODULE_DESCRIPTION("Xilinx DPDMA driver"); > > > > +MODULE_LICENSE("GPL v2"); > > > > > > No MODULE_ALIAS()? > > > > Is it required? Could you please elaborate, to help my understanding? > > did you try builing as modules and testing this? I'm testing it as a loadable kernel module. I'll address rest of your comments. Thanks, -hyun > > -- > ~Vinod ��.n��������+%������w��{.n����z�{��ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
