于 2017年6月14日 GMT+08:00 下午4:32:52, Vinod Koul <vinod.koul@xxxxxxxxx> 写到:
>On Mon, Jun 05, 2017 at 08:33:47PM +0800, Icenowy Zheng wrote:
>> From: Icenowy Zheng <icenowy@xxxxxxxx>
>>
>> Originally we enable a special gate bit when the compatible indicates
>> A23/33.
>>
>> But according to BSP sources and user manuals, more SoCs will need
>this
>> gate bit.
>>
>> So make it a common quirk configured in the config struct.
>>
>> Signed-off-by: Icenowy Zheng <icenowy@xxxxxxxx>
>> ---
>> Changes since original codec patchset v3:
>> - Refactored comments to cover some words found in official
>documents.
>> - Removed the comments when toggling the gate bit.
>>
>> drivers/dma/sun6i-dma.c | 20 +++++++++++++-------
>> 1 file changed, 13 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
>> index a2358780ab2c..252b59c1d1d5 100644
>> --- a/drivers/dma/sun6i-dma.c
>> +++ b/drivers/dma/sun6i-dma.c
>> @@ -101,6 +101,17 @@ struct sun6i_dma_config {
>> u32 nr_max_channels;
>> u32 nr_max_requests;
>> u32 nr_max_vchans;
>> + /*
>> + * In the datasheets/user manuals of newer Allwinner SoCs, a
>special
>> + * bit (bit 2 at register 0x20) is present.
>> + * It's named "DMA MCLK interface circuit auto gating bit" in the
>> + * documents, and the footnote of this register says that this bit
>> + * should be set up when initializing the DMA controller.
>> + * Allwinner A23/A33 user manuals do not have this bit documented,
>> + * however these SoCs really have and need this bit, as seen in the
>> + * BSP kernel source code.
>> + */
>> + bool gate_needed;
>
>Since this is a hw property, why is this not added as an optional DT
>property?
As it's SoC-specified.
Some SoCs need it, and some don't.
SoC info is in compatible, so there's no reason to make it a property.
>
>> };
>>
>> /*
>> @@ -1009,6 +1020,7 @@ static struct sun6i_dma_config
>sun8i_a23_dma_cfg = {
>> .nr_max_channels = 8,
>> .nr_max_requests = 24,
>> .nr_max_vchans = 37,
>> + .gate_needed = true,
>> };
>>
>> static struct sun6i_dma_config sun8i_a83t_dma_cfg = {
>> @@ -1174,13 +1186,7 @@ static int sun6i_dma_probe(struct
>platform_device *pdev)
>> goto err_dma_unregister;
>> }
>>
>> - /*
>> - * sun8i variant requires us to toggle a dma gating register,
>> - * as seen in Allwinner's SDK. This register is not documented
>> - * in the A23 user manual.
>> - */
>> - if (of_device_is_compatible(pdev->dev.of_node,
>> - "allwinner,sun8i-a23-dma"))
>> + if (sdc->cfg->gate_needed)
>> writel(SUN8I_DMA_GATE_ENABLE, sdc->base + SUN8I_DMA_GATE);
>>
>> return 0;
>> --
>> 2.12.2
>>
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