From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from fk-out-0910.google.com ([209.85.128.185]) by www.linuxtv.org with esmtp (Exim 4.63) (envelope-from ) id 1JcrV9-0001tR-2j for linux-dvb@linuxtv.org; Sat, 22 Mar 2008 01:22:24 +0100 Received: by fk-out-0910.google.com with SMTP id z22so2397029fkz.1 for ; Fri, 21 Mar 2008 17:22:19 -0700 (PDT) Message-ID: <47E45138.1030107@googlemail.com> Date: Sat, 22 Mar 2008 00:22:16 +0000 From: Andrea MIME-Version: 1.0 To: linux-dvb@linuxtv.org Content-Type: multipart/mixed; boundary="------------070702080601090906040509" Subject: [linux-dvb] [PATCH] 2/3: implement DMX_SET_BUFFER_SIZE for dvr List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-dvb-bounces@linuxtv.org Errors-To: linux-dvb-bounces+mchehab=infradead.org@linuxtv.org List-ID: This is a multi-part message in MIME format. --------------070702080601090906040509 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit This patch implements the ioctl DMX_SET_BUFFER_SIZE for the dvr. The ioctl used to be supported but not yet implemented. The way it works is that it replaces the ringbuffer with a new one. Beforehand it flushes the old buffer. This means that part of the stream is lost, and reading errors (like overflow) are cleaned. The flushing is not a problem since this operation usually occurs at beginning before start reading. Since the dvr is *always* up and running this change has to be done while the buffer is written: 1) On the userspace side, it is as safe as dvb_dvr_read is now: - dvb_dvr_set_buffer_size locks the mutex - dvb_dvr_read does *not* lock the mutex (the code is there commented out) So as long as one does not call read simultaneously it works properly. Maybe the mutex should be enforced in dvb_dvr_read. 2) On the kernel side The only thing I am not 100% sure about is whether the spin_lock I've used is enough to guarantee synchronization between the new function dvb_dvr_set_buffer_size (which uses spin_lock_irq) and dvb_dmxdev_ts_callback and dvb_dmxdev_section_callback (using spin_lock). But this looks to me the same as all other functions do. I would like to change documentation about DMX_SET_BUFFER_SIZE, but I could not find the source of http://www.linuxtv.org/docs/dvbapi/DVB_Demux_Device.html Andrea --------------070702080601090906040509 Content-Type: text/x-patch; name="size.diff" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="size.diff" diff -r 1886a5ea2f84 linux/drivers/media/dvb/dvb-core/dmxdev.c --- a/linux/drivers/media/dvb/dvb-core/dmxdev.c Fri Mar 21 08:04:55 2008 -0300 +++ b/linux/drivers/media/dvb/dvb-core/dmxdev.c Sat Mar 22 00:07:56 2008 +0000 @@ -259,6 +259,37 @@ static ssize_t dvb_dvr_read(struct file return ret; } +static int dvb_dvr_set_buffer_size(struct dmxdev *dmxdev, + unsigned long size) +{ + struct dvb_ringbuffer *buf = &dmxdev->dvr_buffer; + void *mem; + + if (buf->size == size) + return 0; + + dprintk("function : %s\n", __FUNCTION__); + + spin_lock(&dmxdev->lock); + mem = buf->data; + buf->data = NULL; + buf->size = size; + dvb_ringbuffer_flush(buf); + spin_unlock(&dmxdev->lock); + vfree(mem); + + if (buf->size) { + mem = vmalloc(dmxdev->dvr_buffer.size); + if (!mem) + return -ENOMEM; + spin_lock(&dmxdev->lock); + buf->data = mem; + spin_unlock(&dmxdev->lock); + } + + return 0; +} + static inline void dvb_dmxdev_filter_state_set(struct dmxdev_filter *dmxdevfilter, int state) { @@ -1009,6 +1040,7 @@ static int dvb_dvr_do_ioctl(struct inode { struct dvb_device *dvbdev = file->private_data; struct dmxdev *dmxdev = dvbdev->priv; + unsigned long arg = (unsigned long)parg; int ret; if (mutex_lock_interruptible(&dmxdev->mutex)) @@ -1016,8 +1048,7 @@ static int dvb_dvr_do_ioctl(struct inode switch (cmd) { case DMX_SET_BUFFER_SIZE: - // FIXME: implement - ret = 0; + ret = dvb_dvr_set_buffer_size(dmxdev, arg); break; default: --------------070702080601090906040509 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-dvb mailing list linux-dvb@linuxtv.org http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb --------------070702080601090906040509--