> >> >> Yes, driver frees not used buffers here. >> I think that it's the safest place for this purpose. >> >> > >> >>>> + dma_free_coherent(priv_dev->sysdev, buf- >> >size, >> >>>> + buf->buf, >> >>>> + buf->dma); >> >>>> + spin_lock_irqsave(&priv_dev->lock, flags); >> >>>> + >> >>>> + kfree(buf); >> >>> >> >>>why do you even need this "garbage collector"? >> >> >> >> I need to free not used memory. The once allocated buffer will be >> >> associated with request, but if request.length will be increased in >> >> usb_request then driver will must allocate the bigger buffer. As I >> >> remember I couldn't call dma_free_coherent in interrupt context so I >> >> had to move it to thread handled. This flag was used to avoid going through >> whole aligned_buf_list every time. >> >> In most cases this part will never called int this place >> > >> >Did you try, btw, setting the quirk flag which tells gadget drivers to >> >always allocate buffers aligned to MaxPacketSize? Wouldn't that be enough? >> >> If found only quirk_ep_out_aligned_size flag, but it align only buffer size. >> >> DMA used by this controller must have buffer address aligned to 8. >> I think that on most architecture kmalloc should guarantee such aligned. >> The problem was detected on NXP testing board. >> On my board all buffer address are alignment at least to 8. >> > >This un-aligned request buffer address for 8 occurs for Ethernet Gadget (eg, NCM), >it allocates socket buffer with NET_IP_ALIGN, so the last byte of buffer address >is always 2. Although this can be workaround by setting quirk_avoids_skb_reserve, >but we are not sure if all gadget request buffers can be 8 or Max Packet Size aligned. > Thanks Peter for explanation. I will add quirk_avoids_skb_reserve to avoid using this extra buffers, but I leave this code for safety. -- Cheers, Pawell
