Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753921AbdF1EFV (ORCPT ); Wed, 28 Jun 2017 00:05:21 -0400 Received: from kvm5.telegraphics.com.au ([98.124.60.144]:54110 "EHLO kvm5.telegraphics.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751584AbdF1EEk (ORCPT ); Wed, 28 Jun 2017 00:04:40 -0400 To: "James E.J. Bottomley" , "Martin K. Petersen" , Ondrej Zary Cc: , , Michael Schmitz Message-Id: In-Reply-To: References: From: Finn Thain Subject: [PATCH v4 5/5] g_NCR5380: Re-work PDMA loops Date: Wed, 28 Jun 2017 00:04:37 -0400 (EDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8333 Lines: 226 From: Ondrej Zary The polling loops in pread() and pwrite() can easily become infinite loops and hang the machine. On DTC chips, IRQ can arrive late and we miss it because we only check once. Merge the IRQ check into host buffer wait and add polling limit. Also place a limit on polling for 53C80 registers accessibility. [Use NCR5380_poll_politely2() for register polling. Rely on polling for gated IRQ rather than polling for phase error, like the algorithm in the datasheet. Calculate residual from block count register instead of the loop counter. Factor-out common code as wait_for_53c80_access(). -- F.T.] Signed-off-by: Ondrej Zary Signed-off-by: Finn Thain --- drivers/scsi/g_NCR5380.c | 147 ++++++++++++++++++++++------------------------- 1 file changed, 69 insertions(+), 78 deletions(-) diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c index b1e0a08e49c1..a9e050b65d5f 100644 --- a/drivers/scsi/g_NCR5380.c +++ b/drivers/scsi/g_NCR5380.c @@ -482,6 +482,30 @@ static void generic_NCR5380_release_resources(struct Scsi_Host *instance) release_mem_region(base, region_size); } +/* wait_for_53c80_access - wait for 53C80 registers to become accessible + * @hostdata: scsi host private data + * + * The registers within the 53C80 logic block are inaccessible until + * bit 7 in the 53C400 control status register gets asserted. + */ + +static void wait_for_53c80_access(struct NCR5380_hostdata *hostdata) +{ + int count = 10000; + + do { + if (hostdata->board == BOARD_DTC3181E) + udelay(4); /* DTC436 chip hangs without this */ + if (NCR5380_read(hostdata->c400_ctl_status) & CSR_53C80_REG) + return; + } while (--count > 0); + + scmd_printk(KERN_ERR, hostdata->connected, + "53c80 registers not accessible, device will be reset\n"); + NCR5380_write(hostdata->c400_ctl_status, CSR_RESET); + NCR5380_write(hostdata->c400_ctl_status, CSR_BASE); +} + /** * generic_NCR5380_pread - pseudo DMA receive * @hostdata: scsi host private data @@ -494,18 +518,18 @@ static void generic_NCR5380_release_resources(struct Scsi_Host *instance) static inline int generic_NCR5380_pread(struct NCR5380_hostdata *hostdata, unsigned char *dst, int len) { - int blocks = len / 128; int start = 0; NCR5380_write(hostdata->c400_ctl_status, CSR_BASE | CSR_TRANS_DIR); - NCR5380_write(hostdata->c400_blk_cnt, blocks); - while (1) { - if (NCR5380_read(hostdata->c400_blk_cnt) == 0) + NCR5380_write(hostdata->c400_blk_cnt, len / 128); + + while (start < len) { + if (NCR5380_poll_politely2(hostdata, hostdata->c400_ctl_status, + CSR_HOST_BUF_NOT_RDY, 0, + hostdata->c400_ctl_status, + CSR_GATED_53C80_IRQ, + CSR_GATED_53C80_IRQ, HZ / 64) < 0) break; - if (NCR5380_read(hostdata->c400_ctl_status) & CSR_GATED_53C80_IRQ) - goto out_wait; - while (NCR5380_read(hostdata->c400_ctl_status) & CSR_HOST_BUF_NOT_RDY) - ; /* FIXME - no timeout */ if (hostdata->io_port && hostdata->io_width == 2) insw(hostdata->io_port + hostdata->c400_host_buf, @@ -518,38 +542,19 @@ static inline int generic_NCR5380_pread(struct NCR5380_hostdata *hostdata, hostdata->io + NCR53C400_host_buffer, 128); start += 128; - blocks--; } - if (blocks) { - while (NCR5380_read(hostdata->c400_ctl_status) & CSR_HOST_BUF_NOT_RDY) - ; /* FIXME - no timeout */ - - if (hostdata->io_port && hostdata->io_width == 2) - insw(hostdata->io_port + hostdata->c400_host_buf, - dst + start, 64); - else if (hostdata->io_port) - insb(hostdata->io_port + hostdata->c400_host_buf, - dst + start, 128); - else - memcpy_fromio(dst + start, - hostdata->io + NCR53C400_host_buffer, 128); - - start += 128; - blocks--; - } - - if (!(NCR5380_read(hostdata->c400_ctl_status) & CSR_GATED_53C80_IRQ)) - printk("53C400r: no 53C80 gated irq after transfer"); - -out_wait: - hostdata->pdma_residual = len - start; + hostdata->pdma_residual = NCR5380_read(hostdata->c400_blk_cnt) * 128; - /* wait for 53C80 registers to be available */ - while (!(NCR5380_read(hostdata->c400_ctl_status) & CSR_53C80_REG)) - ; + if (start < len) { + /* Detected a 53c80 interrupt (or worse). Reset 53c400 logic. */ + NCR5380_write(hostdata->c400_ctl_status, CSR_RESET); + NCR5380_write(hostdata->c400_ctl_status, CSR_BASE); + } else + wait_for_53c80_access(hostdata); - if (NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG, + if (hostdata->pdma_residual == 0 && + NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG, BASR_END_DMA_TRANSFER, BASR_END_DMA_TRANSFER, HZ / 64) < 0) scmd_printk(KERN_ERR, hostdata->connected, "%s: End of DMA timeout (%d)\n", @@ -570,36 +575,18 @@ static inline int generic_NCR5380_pread(struct NCR5380_hostdata *hostdata, static inline int generic_NCR5380_pwrite(struct NCR5380_hostdata *hostdata, unsigned char *src, int len) { - int blocks = len / 128; int start = 0; NCR5380_write(hostdata->c400_ctl_status, CSR_BASE); - NCR5380_write(hostdata->c400_blk_cnt, blocks); - while (1) { - if (NCR5380_read(hostdata->c400_ctl_status) & CSR_GATED_53C80_IRQ) - goto out_wait; - - if (NCR5380_read(hostdata->c400_blk_cnt) == 0) + NCR5380_write(hostdata->c400_blk_cnt, len / 128); + + while (start < len) { + if (NCR5380_poll_politely2(hostdata, hostdata->c400_ctl_status, + CSR_HOST_BUF_NOT_RDY, 0, + hostdata->c400_ctl_status, + CSR_GATED_53C80_IRQ, + CSR_GATED_53C80_IRQ, HZ / 64) < 0) break; - while (NCR5380_read(hostdata->c400_ctl_status) & CSR_HOST_BUF_NOT_RDY) - ; // FIXME - timeout - - if (hostdata->io_port && hostdata->io_width == 2) - outsw(hostdata->io_port + hostdata->c400_host_buf, - src + start, 64); - else if (hostdata->io_port) - outsb(hostdata->io_port + hostdata->c400_host_buf, - src + start, 128); - else - memcpy_toio(hostdata->io + NCR53C400_host_buffer, - src + start, 128); - - start += 128; - blocks--; - } - if (blocks) { - while (NCR5380_read(hostdata->c400_ctl_status) & CSR_HOST_BUF_NOT_RDY) - ; // FIXME - no timeout if (hostdata->io_port && hostdata->io_width == 2) outsw(hostdata->io_port + hostdata->c400_host_buf, @@ -612,27 +599,31 @@ static inline int generic_NCR5380_pwrite(struct NCR5380_hostdata *hostdata, src + start, 128); start += 128; - blocks--; } -out_wait: - hostdata->pdma_residual = len - start; + hostdata->pdma_residual = NCR5380_read(hostdata->c400_blk_cnt) * 128; - /* wait for 53C80 registers to be available */ - while (!(NCR5380_read(hostdata->c400_ctl_status) & CSR_53C80_REG)) { - udelay(4); /* DTC436 chip hangs without this */ - /* FIXME - no timeout */ + if (start < len) { + /* Detected a 53c80 interrupt (or worse). Reset 53c400 logic. */ + NCR5380_write(hostdata->c400_ctl_status, CSR_RESET); + NCR5380_write(hostdata->c400_ctl_status, CSR_BASE); + } else + wait_for_53c80_access(hostdata); + + if (hostdata->pdma_residual == 0) { + if (NCR5380_poll_politely(hostdata, TARGET_COMMAND_REG, + TCR_LAST_BYTE_SENT, TCR_LAST_BYTE_SENT, + HZ / 64) < 0) + scmd_printk(KERN_ERR, hostdata->connected, + "%s: Last Byte Sent timeout\n", __func__); + + if (NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG, + BASR_END_DMA_TRANSFER, BASR_END_DMA_TRANSFER, + HZ / 64) < 0) + scmd_printk(KERN_ERR, hostdata->connected, "%s: End of DMA timeout (%d)\n", + __func__, hostdata->pdma_residual); } - while (!(NCR5380_read(TARGET_COMMAND_REG) & TCR_LAST_BYTE_SENT)) - ; // TIMEOUT - - if (NCR5380_poll_politely(hostdata, BUS_AND_STATUS_REG, - BASR_END_DMA_TRANSFER, BASR_END_DMA_TRANSFER, - HZ / 64) < 0) - scmd_printk(KERN_ERR, hostdata->connected, "%s: End of DMA timeout (%d)\n", - __func__, hostdata->pdma_residual); - return 0; } -- 2.13.0