On Tue, Apr 26, 2022 at 10:30 AM Ilpo Järvinen
<ilpo.jarvinen@xxxxxxxxxxxxxxx> wrote:
> On Tue, 26 Apr 2022, Sergey Ryazanov wrote:
>> On Fri, Apr 8, 2022 at 1:37 AM Ricardo Martinez
>> <ricardo.martinez@xxxxxxxxxxxxxxx> wrote:
>>> Data Path Modem AP Interface (DPMAIF) HIF layer provides methods
>>> for initialization, ISR, control and event handling of TX/RX flows.
>>>
>>> DPMAIF TX
>>> Exposes the 'dmpaif_tx_send_skb' function which can be used by the
>>> network device to transmit packets.
>>> The uplink data management uses a Descriptor Ring Buffer (DRB).
>>> First DRB entry is a message type that will be followed by 1 or more
>>> normal DRB entries. Message type DRB will hold the skb information
>>> and each normal DRB entry holds a pointer to the skb payload.
>>>
>>> DPMAIF RX
>>> The downlink buffer management uses Buffer Address Table (BAT) and
>>> Packet Information Table (PIT) rings.
>>> The BAT ring holds the address of skb data buffer for the HW to use,
>>> while the PIT contains metadata about a whole network packet including
>>> a reference to the BAT entry holding the data buffer address.
>>> The driver reads the PIT and BAT entries written by the modem, when
>>> reaching a threshold, the driver will reload the PIT and BAT rings.
>>>
>>> Signed-off-by: Haijun Liu <haijun.liu@xxxxxxxxxxxx>
>>> Signed-off-by: Chandrashekar Devegowda <chandrashekar.devegowda@xxxxxxxxx>
>>> Co-developed-by: Ricardo Martinez <ricardo.martinez@xxxxxxxxxxxxxxx>
>>> Signed-off-by: Ricardo Martinez <ricardo.martinez@xxxxxxxxxxxxxxx>
>>>
>>> From a WWAN framework perspective:
>>> Reviewed-by: Loic Poulain <loic.poulain@xxxxxxxxxx>
>>
>> Reviewed-by: Sergey Ryazanov <ryazanov.s.a@xxxxxxxxx>
>>
>> and a small question below.
>>
>>> diff --git a/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c b/drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c
>>> ...
>>> +static bool t7xx_alloc_and_map_skb_info(const struct dpmaif_ctrl *dpmaif_ctrl,
>>> + const unsigned int size, struct dpmaif_bat_skb *cur_skb)
>>> +{
>>> + dma_addr_t data_bus_addr;
>>> + struct sk_buff *skb;
>>> + size_t data_len;
>>> +
>>> + skb = __dev_alloc_skb(size, GFP_KERNEL);
>>> + if (!skb)
>>> + return false;
>>> +
>>> + data_len = skb_end_pointer(skb) - skb->data;
>>
>> Earlier you use a nice t7xx_skb_data_area_size() function here, but
>> now you opencode it. Is it a consequence of t7xx_common.h removing?
>>
>> I would even encourage you to make this function common and place it
>> into include/linux/skbuff.h with a dedicated patch and call it
>> something like skb_data_size(). Surprisingly, there is no such helper
>> function in the kernel, and several other drivers will benefit from
>> it:
>
> I agree other than the name. IMHO, skb_data_size sounds too much "data
> size" which it exactly isn't but just how large the memory area is (we
> already have "datalen" anyway and on language level, those two don't sound
> different at all). The memory area allocated may or may not have actual
> data in it, I suggested adding "area" into it.
I agree, using the "area" word in the helper name gives more clue
about its purpose, thanks.
--
Sergey
