Re: [PATCH 06/32] spi: dw: Add support for the Kendryte K210 SoC

[Damien Le Moal <Damien.LeMoal@xxxxxxx>]

On 2020/11/10 6:55, Rob Herring wrote:
> On Mon, Nov 09, 2020 at 09:39:19PM +0000, Damien Le Moal wrote:
>> On 2020/11/10 6:22, Serge Semin wrote:
>>> On Sat, Nov 07, 2020 at 05:13:54PM +0900, Damien Le Moal wrote:
>>>> The DW SPI master of the Kendryte K210 RISC-V SoC uses the 32-bits
>>>> ctrlr0 register format. This SoC is also quite slow and gets significant
>>>> SD card performance improvements from using no-delay polled transfers.
>>>> Add the dw_spi_k210_init() function tied to the
>>>> "canaan,kendryte-k210-spi" compatible string to set the
>>>> DW_SPI_CAP_DFS_32 and DW_SPI_CAP_POLL_NODELAY DW SPI capability fields
>>>> for this SoC.
>>>>
>>>> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
>>>> ---
>>>>  drivers/spi/spi-dw-mmio.c | 9 +++++++++
>>>>  1 file changed, 9 insertions(+)
>>>>
>>>> diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
>>>> index 3f1bc384cb45..a00def6c5b39 100644
>>>> --- a/drivers/spi/spi-dw-mmio.c
>>>> +++ b/drivers/spi/spi-dw-mmio.c
>>>> @@ -223,6 +223,14 @@ static int dw_spi_keembay_init(struct platform_device *pdev,
>>>>  	return 0;
>>>>  }
>>>>  
>>>> +static int dw_spi_k210_init(struct platform_device *pdev,
>>>> +			    struct dw_spi_mmio *dwsmmio)
>>>> +{
>>>> +	dwsmmio->dws.caps = DW_SPI_CAP_DFS_32 | DW_SPI_CAP_POLL_NODELAY;
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>>  static int dw_spi_mmio_probe(struct platform_device *pdev)
>>>>  {
>>>>  	int (*init_func)(struct platform_device *pdev,
>>>> @@ -340,6 +348,7 @@ static const struct of_device_id dw_spi_mmio_of_match[] = {
>>>>  	{ .compatible = "snps,dwc-ssi-1.01a", .data = dw_spi_dwc_ssi_init},
>>>>  	{ .compatible = "intel,keembay-ssi", .data = dw_spi_keembay_init},
>>>>  	{ .compatible = "microchip,sparx5-spi", dw_spi_mscc_sparx5_init},
>>>
>>>> +	{ .compatible = "canaan,kendryte-k210-spi", .data = dw_spi_k210_init},
>>>
>>> Other than the comments from Sean and Mark regarding the DFS_32
>>> feature runtime detectability, I couldn't find a patch with adding the
>>> new new compatible string into the DW APB SSI DT schema. Have I missed
>>> it? If I haven't could you add one to the next version of the series?
>>
>> Yes, I will. I forgot to change the DW DT binding doc for this. I did add a
>> patch for the "polling" property but forgot the compatible string.
>>
>> In any case, I think that this new compatible string change can be dropped by
>> switching to automatically detecting the DFS32 and using a different solution
>> than the polling property change I sent for the RX fifo overflow problem.
> 
> No, new SoC needs new compatible string. Especially if a new vendor. 

My apologies for the bad wording: I meant to say the change to the list of
compatible strings that the DW SPI support would not be needed. So from the DW
SPI point of view, there would be no new compatible string to add/document.

> 
>>
>> I am still going through all the emails trying to understand what to try next to
>> avoid the polling "hack".
> 
> Use compatible.

Yes, that is what this patch used. Again, I think there is a chance this change
can be dropped.

> 
> Rob
> 


-- 
Damien Le Moal
Western Digital Research