2018-09-12 13:35 GMT+09:00 Vinod [off-list ref]:

On 12-09-18, 12:01, Masahiro Yamada wrote:

quoted

Hi Vinod,


2018-09-11 16:00 GMT+09:00 Vinod [off-list ref]:

quoted

On 24-08-18, 10:41, Masahiro Yamada wrote:

quoted

+/* mc->vc.lock must be held by caller */
+static u32 __uniphier_mdmac_get_residue(struct uniphier_mdmac_desc *md)
+{
+     u32 residue = 0;
+     int i;
+
+     for (i = md->sg_cur; i < md->sg_len; i++)
+             residue += sg_dma_len(&md->sgl[i]);

so if the descriptor is submitted to hardware, we return the descriptor
length, which is not correct.

Two cases are required to be handled:
1. Descriptor is in queue (IMO above logic is fine for that, but it can
be calculated at descriptor submit and looked up here)

Where do you want it to be calculated?

where is it calculated now?

Please see __uniphier_mdmac_handle().


It gets the address and size by sg_dma_address(), sg_dma_len()
just before setting them to the hardware registers.


       sg = &md->sgl[md->sg_cur];

       if (md->dir == DMA_MEM_TO_DEV) {
               src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
               src_addr = sg_dma_address(sg);
               dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
               dest_addr = 0;
       } else {
               src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
               src_addr = 0;
               dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
               dest_addr = sg_dma_address(sg);
       }

quoted

This hardware provides only simple registers (address and size)
for one-shot transfer instead of descriptors.

So, I used sgl as-is because I did not see a good reason
to transform sgl to another data structure.

quoted

quoted

this seems missing stuff. Where do you do register calculation for the
descriptor and where is slave_config here, how do you know where to
send/receive data form/to (peripheral)

This dmac is really simple, and un-flexible.

The peripheral address to send/receive data from/to is hard-weird.
cfg->{src_addr,dst_addr} is not configurable.

Look at __uniphier_mdmac_handle().
'dest_addr' and 'src_addr' must be set to 0 for the peripheral.

Fair enough, what about other values like addr_width and maxburst?

None of them is configurable.



-- 
Best Regards
Masahiro Yamada