> > 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. Peter
