Re: [PATCH v7 06/12] dmaengine: ti: Add cppi5 header for K3 NAVSS/UDMA

Peter Ujfalusi
2019-12-20T10:42:05Z

Hi Vinod,

On 20/12/2019 11.54, Vinod Koul wrote:
> On 09-12-19, 11:43, Peter Ujfalusi wrote:
>
>> +#define CPPI5_INFO2_DESC_RETPUSHPOLICY BIT(16)
>> +#define CPPI5_INFO2_DESC_RETP_MASK GENMASK(18, 16)
>> +
>> +#define CPPI5_INFO2_DESC_RETQ_SHIFT (0)
>> +#define CPPI5_INFO2_DESC_RETQ_MASK GENMASK(15, 0)
>> +
>> +#define CPPI5_INFO3_DESC_SRCTAG_SHIFT (16U)
>> +#define CPPI5_INFO3_DESC_SRCTAG_MASK GENMASK(31, 16)
>> +#define CPPI5_INFO3_DESC_DSTTAG_SHIFT (0)
>> +#define CPPI5_INFO3_DESC_DSTTAG_MASK GENMASK(15, 0)
>> +
>> +#define CPPI5_BUFINFO1_HDESC_DATA_LEN_SHIFT (0)
>> +#define CPPI5_BUFINFO1_HDESC_DATA_LEN_MASK GENMASK(27, 0)
>> +
>> +#define CPPI5_OBUFINFO0_HDESC_BUF_LEN_SHIFT (0)
>> +#define CPPI5_OBUFINFO0_HDESC_BUF_LEN_MASK GENMASK(27, 0)
>
> I think you can remove the SHIFT defines and use ffs() to get the bit
> position for shift

Right. I'll convert to use ffs()

>
>> +static inline u32 cppi5_hdesc_calc_size(bool epib, u32 psdata_size,
>> + u32 sw_data_size)
>> +{
>> + u32 desc_size;
>> +
>> + if (psdata_size > CPPI5_INFO0_HDESC_PSDATA_MAX_SIZE)
>> + return 0;
>> +
>> + desc_size = sizeof(struct cppi5_host_desc_t) + psdata_size +
>> + sw_data_size;
>
> I think there was an API for this kind of mem allocation of struct and
> buffer attached...

The returned size is not only used when allocating memory or setting up
the dma_pool, but for UDMAP's fetch size parameter.

>> +static inline void cppi5_hdesc_reset_hbdesc(struct cppi5_host_desc_t *desc)
>> +{
>> + desc->hdr = (struct cppi5_desc_hdr_t) { 0 };
>> + desc->next_desc = 0;
>
> would this not be superfluous? Or if you want a memset call?

The intention is to reset the header and the next descriptor link but
leave the backing buffer information intact. This allows the reuse of a
descriptor+buffer and we only need to set the header bits + next
descriptor pointer if any.

>> +static inline u32 *cppi5_hdesc_get_psdata32(struct cppi5_host_desc_t *desc)
>> +{
>> + return (u32 *)cppi5_hdesc_get_psdata(desc);
>
> you dont need casts away from void *

Hrm, or just remove this, clients can use the cppi5_hdesc_get_psdata()
directly.

- Péter