Hi Ben,
On Tue, Apr 15, 2014 at 11:54 AM, Ben Dooks <[email protected]> wrote:
>>> static struct dma_chan *shdma_of_xlate(struct of_phandle_args
>>> *dma_spec,
>>> struct of_dma *ofdma)
>>> {
>>> + struct platform_device *pdev = ofdma->of_dma_data;
>>> u32 id = dma_spec->args[0];
>>> dma_cap_mask_t mask;
>>> struct dma_chan *chan;
>>>
>>> - if (dma_spec->args_count != 1)
>>> + if (dma_spec->args_count == 2) {
>>> + struct shdma_of_state *state =
>>> platform_get_drvdata(pdev);
>>> + struct shdma_of_client *client;
>>> +
>>> + client = shdma_of_find_client(state, id);
>>> + if (!client) {
>>> + client = devm_kzalloc(&pdev->dev,
>>> sizeof(*client),
>>> + GFP_KERNEL);
>>> + if (!client)
>>> + return NULL;
>>> +
>>> + client->index =
>>> atomic_inc_return(&of_slave_index);
>>> + client->cfg.slave_id = id;
>>> + client->cfg.mid_rid = id;
>>> + client->cfg.chcr = dma_spec->args[1];
>>
>>
>> Can you explain the purpose of setting the chcr in DT? For all I can
>> tell, this should come from the device driver when that calls the
>> dma_slave_config function, unlike the mid_rid value.
>
>
> See previous note about transfer-widths and register-sizes not always
> matching. I also do not have any idea about other SoCs in the series
> if there are any differences between channel settings.
If you look for sh_dmae_slave_config in arch/arm arch/sh, you find the values
for the existing board support.
The same device always seem to use the same value, i.e. MMC always uses
32-bit, SCIF uses 8-bit, SDHI uses 16-bit. So I think it could be hardcoded
in the device driver (passed via enum dma_slave_buswidth {src,dst}_addr_width
in dma_slave_config?), and you can drop the field in the bindings.
Notes:
- RSPI is special: on SH, it's 16-bit, while QSPI on R-Car uses 8-bit.
- SDHI uses 32-bit according to the R-Car docs, but the (working) code
uses 16-bit?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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