From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kapsi.fi ([217.30.184.167]:54396 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754857AbbG1AuU (ORCPT ); Mon, 27 Jul 2015 20:50:20 -0400 Subject: Re: [PATCHv2 8/9] hackrf: add support for transmitter To: Hans Verkuil , linux-media@vger.kernel.org References: <1437030298-20944-1-git-send-email-crope@iki.fi> <1437030298-20944-9-git-send-email-crope@iki.fi> <55A91474.4000801@xs4all.nl> <55B692D3.2070601@iki.fi> <55B696D0.2000700@xs4all.nl> From: Antti Palosaari Message-ID: <55B6D1C9.30807@iki.fi> Date: Tue, 28 Jul 2015 03:50:17 +0300 MIME-Version: 1.0 In-Reply-To: <55B696D0.2000700@xs4all.nl> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 07/27/2015 11:38 PM, Hans Verkuil wrote: > On 07/27/2015 10:21 PM, Antti Palosaari wrote: >> On 07/17/2015 05:43 PM, Hans Verkuil wrote: >>> On 07/16/2015 09:04 AM, Antti Palosaari wrote: >>>> HackRF SDR device has both receiver and transmitter. There is limitation >>>> that receiver and transmitter cannot be used at the same time >>>> (half-duplex operation). That patch implements transmitter support to >>>> existing receiver only driver. >>>> >>>> Cc: Hans Verkuil >>>> Signed-off-by: Antti Palosaari >>>> --- >>>> drivers/media/usb/hackrf/hackrf.c | 787 +++++++++++++++++++++++++++----------- >>>> 1 file changed, 572 insertions(+), 215 deletions(-) >>>> >>> >>> >>>> @@ -611,8 +751,15 @@ static int hackrf_queue_setup(struct vb2_queue *vq, >>>> unsigned int *nplanes, unsigned int sizes[], void *alloc_ctxs[]) >>>> { >>>> struct hackrf_dev *dev = vb2_get_drv_priv(vq); >>>> + struct usb_interface *intf = dev->intf; >>>> + int ret; >>>> >>>> - dev_dbg(dev->dev, "nbuffers=%d\n", *nbuffers); >>>> + dev_dbg(&intf->dev, "nbuffers=%d\n", *nbuffers); >>>> + >>>> + if (test_and_set_bit(QUEUE_SETUP, &dev->flags)) { >>>> + ret = -EBUSY; >>>> + goto err; >>>> + } >>> >>> This doesn't work. The bit is only cleared when start_streaming fails or >>> stop_streaming is called. But the application can also call REQBUFS again >>> or just close the file handle, and then QUEUE_SETUP should also be cleared. >>> >>> But why is this here in the first place? It doesn't seem to do anything >>> useful (except mess up the v4l2-compliance tests). >>> >>> I've removed it and it now seems to work OK. >> >> It is there to block simultaneous use of receiver and transmitter. >> Device could operate only single mode at the time - receiving or >> transmitting. Driver shares streaming buffers. >> >> Any idea how I can easily implement correct blocking? > > Since each video_device struct has its own vb2_queue I wouldn't put the check > here. Instead, put the check in the start_streaming callback. And the check > is easy enough: if you want to start capturing, then call > vb2_is_streaming(&tx_vb2_queue). If you want to start output, then call > vb2_is_streaming(&rx_vb2_queue). If the other 'side' is streaming, then > return EBUSY. > > It's perfectly valid to allocate the buffers, but actually streaming is an > exclusive operation. Currently there is two queues, but only single buffer. If I do check on start_streaming() it is too late as buffers are queue during buf_queue() which is called earlier (and now both sides are added to same queued_bufs lists, which messes up). regards Antti -- http://palosaari.fi/