Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755380AbbLGDQa (ORCPT ); Sun, 6 Dec 2015 22:16:30 -0500 Received: from kvm5.telegraphics.com.au ([98.124.60.144]:36907 "EHLO kvm5.telegraphics.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755132AbbLGDQ3 (ORCPT ); Sun, 6 Dec 2015 22:16:29 -0500 Date: Mon, 7 Dec 2015 14:16:14 +1100 (AEDT) From: Finn Thain To: Ondrej Zary cc: Michael Schmitz , linux-m68k@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 77/71] ncr5380: Fix wait for 53C80 registers registers after PDMA In-Reply-To: <1449443866-27296-1-git-send-email-linux@rainbow-software.org> Message-ID: References: <20151118083455.331768508@telegraphics.com.au> <1449443866-27296-1-git-send-email-linux@rainbow-software.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3692 Lines: 105 On Mon, 7 Dec 2015, Ondrej Zary wrote: > The check for 53C80 registers accessibility was commented out because > it was broken (inverted). Fix and enable it. > > Signed-off-by: Ondrej Zary > --- > drivers/scsi/g_NCR5380.c | 37 ++++++------------------------------- > 1 file changed, 6 insertions(+), 31 deletions(-) > > diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c > index 038dddf..a7479c6 100644 > --- a/drivers/scsi/g_NCR5380.c > +++ b/drivers/scsi/g_NCR5380.c > @@ -603,14 +603,10 @@ static inline int NCR5380_pread(struct Scsi_Host *instance, unsigned char *dst, > if (!(NCR5380_read(hostdata->c400_ctl_status) & CSR_GATED_53C80_IRQ)) > printk("53C400r: no 53C80 gated irq after transfer"); > > -#if 0 > - /* > - * DON'T DO THIS - THEY NEVER ARRIVE! > - */ > - printk("53C400r: Waiting for 53C80 registers\n"); > - while (NCR5380_read(hostdata->c400_ctl_status) & CSR_53C80_REG) > + /* wait for 53C80 registers to be available */ > + while (!(NCR5380_read(hostdata->c400_ctl_status) & CSR_53C80_REG)) > ; In the previous patch, udelay(4) was added to a CSR_GATED_53C80_IRQ polling loop. It is interesting that you don't need it here when polling CSR_53C80_REG. > -#endif > + > if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_END_DMA_TRANSFER)) > printk(KERN_ERR "53C400r: no end dma signal\n"); > > @@ -632,7 +628,6 @@ static inline int NCR5380_pwrite(struct Scsi_Host *instance, unsigned char *src, > struct NCR5380_hostdata *hostdata = shost_priv(instance); > int blocks = len / 128; > int start = 0; > - int i; > > NCR5380_write(hostdata->c400_ctl_status, CSR_BASE); > NCR5380_write(hostdata->c400_blk_cnt, blocks); > @@ -681,36 +676,16 @@ static inline int NCR5380_pwrite(struct Scsi_Host *instance, unsigned char *src, > blocks--; > } > > -#if 0 > - printk("53C400w: waiting for registers to be available\n"); > - THEY NEVER DO ! while (NCR5380_read(hostdata->c400_ctl_status) & CSR_53C80_REG); > - printk("53C400w: Got em\n"); > -#endif > - > - /* Let's wait for this instead - could be ugly */ > - /* All documentation says to check for this. Maybe my hardware is too > - * fast. Waiting for it seems to work fine! KLL > - */ > - while (!(i = NCR5380_read(hostdata->c400_ctl_status) & CSR_GATED_53C80_IRQ)) { > + /* wait for 53C80 registers to be available */ > + while (!(NCR5380_read(hostdata->c400_ctl_status) & CSR_53C80_REG)) { > udelay(4); /* DTC436 chip hangs without this */ ... based on the above, this udelay is probably not needed. (Or perhaps it is only needed once, in between the final host_buf register access and the first ctl_status access??) Is there any reference in the docs to timing sensitivity? > /* FIXME - no timeout */ > } > > - /* > - * I know. i is certainly != 0 here but the loop is new. See previous > - * comment. > - */ Thanks for cleaning up this mess! -- > - if (i) { > - if (!((i = NCR5380_read(BUS_AND_STATUS_REG)) & BASR_END_DMA_TRANSFER)) > - printk(KERN_ERR "53C400w: No END OF DMA bit - WHOOPS! BASR=%0x\n", i); > - } else > - printk(KERN_ERR "53C400w: no 53C80 gated irq after transfer (last block)\n"); > - > -#if 0 > if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_END_DMA_TRANSFER)) { > printk(KERN_ERR "53C400w: no end dma signal\n"); > } > -#endif > + > while (!(NCR5380_read(TARGET_COMMAND_REG) & TCR_LAST_BYTE_SENT)) > ; // TIMEOUT > return 0; > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/