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    SubjectRe: [PATCH 04/22] atari_NCR5380: Remove DMA_MIN_SIZE macro
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    On 03/14/2016 05:27 AM, Finn Thain wrote:
    > Only the atari_scsi and sun3_scsi drivers define DMA_MIN_SIZE.
    > Both drivers also define NCR5380_dma_xfer_len, which means
    > DMA_MIN_SIZE is redundant.
    >
    > This removes another discrepancy between the two core drivers.
    >
    > Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
    >
    > ---
    > drivers/scsi/atari_NCR5380.c | 16 ++++++++--------
    > drivers/scsi/atari_scsi.c | 4 +++-
    > drivers/scsi/sun3_scsi.c | 16 ++++++----------
    > 3 files changed, 17 insertions(+), 19 deletions(-)
    >
    > Index: linux/drivers/scsi/atari_NCR5380.c
    > ===================================================================
    > --- linux.orig/drivers/scsi/atari_NCR5380.c 2016-03-14 15:26:23.000000000 +1100
    > +++ linux/drivers/scsi/atari_NCR5380.c 2016-03-14 15:26:26.000000000 +1100
    > @@ -1857,12 +1857,11 @@ static void NCR5380_information_transfer
    > d = cmd->SCp.ptr;
    > }
    > /* this command setup for dma yet? */
    > - if ((count >= DMA_MIN_SIZE) && (sun3_dma_setup_done != cmd)) {
    > - if (cmd->request->cmd_type == REQ_TYPE_FS) {
    > - sun3scsi_dma_setup(instance, d, count,
    > - rq_data_dir(cmd->request));
    > - sun3_dma_setup_done = cmd;
    > - }
    > + if (sun3_dma_setup_done != cmd &&
    > + sun3scsi_dma_xfer_len(count, cmd) > 0) {
    > + sun3scsi_dma_setup(instance, d, count,
    > + rq_data_dir(cmd->request));
    > + sun3_dma_setup_done = cmd;
    > }
    > #ifdef SUN3_SCSI_VME
    > dregs->csr |= CSR_INTR;
    > @@ -1927,7 +1926,7 @@ static void NCR5380_information_transfer
    > #endif
    > transfersize = NCR5380_dma_xfer_len(instance, cmd, phase);
    >
    > - if (transfersize >= DMA_MIN_SIZE) {
    > + if (transfersize > 0) {
    > len = transfersize;
    > cmd->SCp.phase = phase;
    > if (NCR5380_transfer_dma(instance, &phase,
    > @@ -2366,7 +2365,8 @@ static void NCR5380_reselect(struct Scsi
    > d = tmp->SCp.ptr;
    > }
    > /* setup this command for dma if not already */
    > - if ((count >= DMA_MIN_SIZE) && (sun3_dma_setup_done != tmp)) {
    > + if (sun3_dma_setup_done != tmp &&
    > + sun3scsi_dma_xfer_len(count, tmp) > 0) {
    > sun3scsi_dma_setup(instance, d, count,
    > rq_data_dir(tmp->request));
    > sun3_dma_setup_done = tmp;
    > Index: linux/drivers/scsi/atari_scsi.c
    > ===================================================================
    > --- linux.orig/drivers/scsi/atari_scsi.c 2016-03-14 15:26:23.000000000 +1100
    > +++ linux/drivers/scsi/atari_scsi.c 2016-03-14 15:26:26.000000000 +1100
    > @@ -87,7 +87,6 @@
    >
    > #define SUPPORT_TAGS
    > #define MAX_TAGS 32
    > -#define DMA_MIN_SIZE 32
    >
    > #define NCR5380_implementation_fields /* none */
    >
    > @@ -605,6 +604,9 @@ static unsigned long atari_dma_xfer_len(
    > {
    > unsigned long possible_len, limit;
    >
    > + if (wanted_len < 32)
    > + return 0;
    > +
    > if (IS_A_TT())
    > /* TT SCSI DMA can transfer arbitrary #bytes */
    > return wanted_len;
    > Index: linux/drivers/scsi/sun3_scsi.c
    > ===================================================================
    > --- linux.orig/drivers/scsi/sun3_scsi.c 2016-03-14 15:26:23.000000000 +1100
    > +++ linux/drivers/scsi/sun3_scsi.c 2016-03-14 15:26:26.000000000 +1100
    > @@ -39,9 +39,6 @@
    > /* Definitions for the core NCR5380 driver. */
    >
    > /* #define SUPPORT_TAGS */
    > -/* minimum number of bytes to do dma on */
    > -#define DMA_MIN_SIZE 129
    > -
    > /* #define MAX_TAGS 32 */
    >
    > #define NCR5380_implementation_fields /* none */
    > @@ -61,7 +58,7 @@
    > #define NCR5380_dma_residual(instance) \
    > sun3scsi_dma_residual(instance)
    > #define NCR5380_dma_xfer_len(instance, cmd, phase) \
    > - sun3scsi_dma_xfer_len(cmd->SCp.this_residual, cmd, !((phase) & SR_IO))
    > + sun3scsi_dma_xfer_len(cmd->SCp.this_residual, cmd)
    >
    > #define NCR5380_acquire_dma_irq(instance) (1)
    > #define NCR5380_release_dma_irq(instance)
    > @@ -262,14 +259,13 @@ static inline unsigned long sun3scsi_dma
    > return last_residual;
    > }
    >
    > -static inline unsigned long sun3scsi_dma_xfer_len(unsigned long wanted,
    > - struct scsi_cmnd *cmd,
    > - int write_flag)
    > +static inline unsigned long sun3scsi_dma_xfer_len(unsigned long wanted_len,
    > + struct scsi_cmnd *cmd)
    > {
    > - if (cmd->request->cmd_type == REQ_TYPE_FS)
    > - return wanted;
    > - else
    > + if (wanted_len < 129 || cmd->request->cmd_type != REQ_TYPE_FS)
    > return 0;
    > +
    > + return wanted_len;
    > }
    >
    > static inline int sun3scsi_dma_start(unsigned long count, unsigned char *data)
    >
    >
    I still would keep the 'DMA_MIN_LEN' definition around for
    sun3_scsi.c; makes it a bit more obvious what the magic number '129'
    is supposed to mean.

    Cheers,

    Hannes
    --
    Dr. Hannes Reinecke Teamlead Storage & Networking
    hare@suse.de +49 911 74053 688
    SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
    GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
    HRB 21284 (AG Nürnberg)

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