Re: [PATCH RFC 1/8] dmaengine: Actions: get rid of bit fields from dma descriptor

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Mon, May 11, 2020 at 04:15:57PM +0530, Amit Tomer wrote:
> Hi
> 
> Thanks for the reply.
> 
> > I'm in favor of getting rid of bitfields due to its not so defined way of
> > working (and forgive me for using it in first place) but I don't quite like
> > the current approach.
> 
> Because , its less readable the way we are writing to those different fields ?
> But this can be made more verbose by adding some comments around .
> 

I don't like the way the hw linked lists are accessed (using an array with
enums).

> > Rather I'd like to have custom bitmasks (S900/S700/S500?) for writing to those
> > fields.
> >
> I think S900 and S500 are same as pointed out by Cristian. and I didn't get by
> creating custom bitmasks for it ?
> 
> Did you mean function like:
> 
> lli->hw[OWL_DMADESC_FLEN]= llc_hw_FLEN(len, FCNT_VALUE, FCNT_SHIFT);
> 

I meant to keep using old struct for accessing the linked list and replacing
bitfields with masks as below:

struct owl_dma_lli_hw {
	...
        u32     flen;
        u32     fcnt;
	...
};

hw->flen = len & OWL_S900_DMA_FLEN_MASK;
hw->fcnt = 1 & OWL_S900_DMA_FCNT_MASK;

Then you can use different masks for S700/S900 based on the compatible.

Thanks,
Mani

> Thanks
> -Amit