From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylylov Subject: Re: [Alsa-devel] Au1550 OSS driver issues Date: Mon, 07 Nov 2005 22:58:22 +0300 Message-ID: <436FB1DE.6010405@ru.mvista.com> References: <43452054.2090305@ru.mvista.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------050909010902020204030508" Return-path: In-Reply-To: <43452054.2090305@ru.mvista.com> Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org To: Linux MIPS Development Cc: alsa-devel@lists.sourceforge.net, dan@embeddededge.com, Pete Popov , Konstantin Baidarov , Manish Lachwani List-Id: alsa-devel@alsa-project.org This is a multi-part message in MIME format. --------------050909010902020204030508 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Hello, I wrote: > We have found some issues with Au1550 AC'97 OSS driver in 2.6 > (sound/oss/au1550_ac97.c), though it also should concern 2.4 driver > (drivers/sound/au1550_psc.c). > First, we don't think that using readl() calls instead of au_readl() is > correct -- readl() is subject to byte-swapping etc., so may not work in > BE mode anymore and au_readl() is intended for embedded Au1550 devices for > which the byte swapping issue is resolved automagically, and BTW the same > PSC_AC97STAT register is read "both ways" in the driver. ... for no apparent reason? > That's what the first patch is about. > Second, start_dac() grabs a spinlock already held by its caller, > au1550_write(). This doesn't show up with the standard UP spinlock > impelmentation but when the different one (mutex based) is in use, a > lockup happens. The second patch demonstates a possible solution but > here's a question: why there's no "symmetric" spinlock logic in > start_adc(), may be here exits another potential issue? After having a look at sound/oss/au1000.c, here's an updated patch that deals with "nested" spinlocks the same way that driver does, and adds spinlock to start_adc() as well. WBR, Sergei --------------050909010902020204030508 Content-Type: text/plain; name="au1550_ac97_readl.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="au1550_ac97_readl.patch" Signed-off-by: Konstantin Baydarov Signed-off-by: Sergei Shtylyov Index: linux/sound/oss/au1550_ac97.c =================================================================== --- linux.orig/sound/oss/au1550_ac97.c +++ linux/sound/oss/au1550_ac97.c @@ -463,7 +463,7 @@ stop_dac(struct au1550_state *s) /* Wait for Transmit Busy to show disabled. */ do { - stat = readl((void *)PSC_AC97STAT); + stat = au_readl(PSC_AC97STAT); au_sync(); } while ((stat & PSC_AC97STAT_TB) != 0); @@ -492,7 +492,7 @@ stop_adc(struct au1550_state *s) /* Wait for Receive Busy to show disabled. */ do { - stat = readl((void *)PSC_AC97STAT); + stat = au_readl(PSC_AC97STAT); au_sync(); } while ((stat & PSC_AC97STAT_RB) != 0); @@ -542,7 +542,7 @@ set_xmit_slots(int num_channels) /* Wait for Device ready. */ do { - stat = readl((void *)PSC_AC97STAT); + stat = au_readl(PSC_AC97STAT); au_sync(); } while ((stat & PSC_AC97STAT_DR) == 0); } @@ -574,7 +574,7 @@ set_recv_slots(int num_channels) /* Wait for Device ready. */ do { - stat = readl((void *)PSC_AC97STAT); + stat = au_readl(PSC_AC97STAT); au_sync(); } while ((stat & PSC_AC97STAT_DR) == 0); } @@ -1989,7 +1989,7 @@ au1550_probe(void) /* Wait for PSC ready. */ do { - val = readl((void *)PSC_AC97STAT); + val = au_readl(PSC_AC97STAT); au_sync(); } while ((val & PSC_AC97STAT_SR) == 0); @@ -2012,7 +2012,7 @@ au1550_probe(void) /* Wait for Device ready. */ do { - val = readl((void *)PSC_AC97STAT); + val = au_readl(PSC_AC97STAT); au_sync(); } while ((val & PSC_AC97STAT_DR) == 0); --------------050909010902020204030508 Content-Type: text/plain; name="au1550_ac7-spinlocks.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="au1550_ac7-spinlocks.patch" Signed-off-by: Sergei Shtylyov Index: sound/oss/au1550_ac97.c =================================================================== --- sound/oss/au1550_ac97.c~ 10 Jul 2005 10:29:03 -0000 +++ sound/oss/au1550_ac97.c 7 Nov 2005 18:14:59 -0000 @@ -607,11 +607,14 @@ static void start_adc(struct au1550_state *s) { struct dmabuf *db = &s->dma_adc; + unsigned long flags; int i; if (!db->stopped) return; + spin_lock_irqsave(&s->lock, flags); + /* Put two buffers on the ring to get things started. */ for (i=0; i<2; i++) { @@ -630,6 +633,8 @@ start_adc(struct au1550_state *s) au_sync(); db->stopped = 0; + + spin_unlock_irqrestore(&s->lock, flags); } static int @@ -1181,8 +1186,11 @@ au1550_write(struct file *file, const ch if (db->nextOut >= db->rawbuf + db->dmasize) db->nextOut -= db->dmasize; db->total_bytes += db->dma_fragsize; - if (db->dma_qcount == 0) + if (db->dma_qcount == 0) { + spin_unlock(&s->lock); start_dac(s); + spin_lock(&s->lock); + } db->dma_qcount++; } spin_unlock_irqrestore(&s->lock, flags); --------------050909010902020204030508--