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SubjectRe: [PATCH] NCR5380: Support chained sg lists
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On 11/06/19 3:25 PM, Finn Thain wrote:

> My understanding is that support for chained scatterlists is to
> become mandatory for LLDs.
>
> Cc: Michael Schmitz <schmitzmic@gmail.com>
> Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Michael Schmitz <schmitzmic@gmail.com>
> ---
> drivers/scsi/NCR5380.c | 41 ++++++++++++++++++-----------------------
> 1 file changed, 18 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
> index d9fa9cf2fd8b..536426f25e86 100644
> --- a/drivers/scsi/NCR5380.c
> +++ b/drivers/scsi/NCR5380.c
> @@ -149,12 +149,10 @@ static inline void initialize_SCp(struct scsi_cmnd *cmd)
>
> if (scsi_bufflen(cmd)) {
> cmd->SCp.buffer = scsi_sglist(cmd);
> - cmd->SCp.buffers_residual = scsi_sg_count(cmd) - 1;
> cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
> cmd->SCp.this_residual = cmd->SCp.buffer->length;
> } else {
> cmd->SCp.buffer = NULL;
> - cmd->SCp.buffers_residual = 0;
> cmd->SCp.ptr = NULL;
> cmd->SCp.this_residual = 0;
> }
> @@ -163,6 +161,17 @@ static inline void initialize_SCp(struct scsi_cmnd *cmd)
> cmd->SCp.Message = 0;
> }
>
> +static inline void advance_sg_buffer(struct scsi_cmnd *cmd)
> +{
> + struct scatterlist *s = cmd->SCp.buffer;
> +
> + if (!cmd->SCp.this_residual && s && !sg_is_last(s)) {
> + cmd->SCp.buffer = sg_next(s);
> + cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
> + cmd->SCp.this_residual = cmd->SCp.buffer->length;
> + }
> +}
> +
> /**
> * NCR5380_poll_politely2 - wait for two chip register values
> * @hostdata: host private data
> @@ -1670,12 +1679,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
> sun3_dma_setup_done != cmd) {
> int count;
>
> - if (!cmd->SCp.this_residual && cmd->SCp.buffers_residual) {
> - ++cmd->SCp.buffer;
> - --cmd->SCp.buffers_residual;
> - cmd->SCp.this_residual = cmd->SCp.buffer->length;
> - cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
> - }
> + advance_sg_buffer(cmd);
>
> count = sun3scsi_dma_xfer_len(hostdata, cmd);
>
> @@ -1725,15 +1729,11 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
> * scatter-gather list, move onto the next one.
> */
>
> - if (!cmd->SCp.this_residual && cmd->SCp.buffers_residual) {
> - ++cmd->SCp.buffer;
> - --cmd->SCp.buffers_residual;
> - cmd->SCp.this_residual = cmd->SCp.buffer->length;
> - cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
> - dsprintk(NDEBUG_INFORMATION, instance, "%d bytes and %d buffers left\n",
> - cmd->SCp.this_residual,
> - cmd->SCp.buffers_residual);
> - }
> + advance_sg_buffer(cmd);
> + dsprintk(NDEBUG_INFORMATION, instance,
> + "this residual %d, sg ents %d\n",
> + cmd->SCp.this_residual,
> + sg_nents(cmd->SCp.buffer));
>
> /*
> * The preferred transfer method is going to be
> @@ -2126,12 +2126,7 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
> if (sun3_dma_setup_done != tmp) {
> int count;
>
> - if (!tmp->SCp.this_residual && tmp->SCp.buffers_residual) {
> - ++tmp->SCp.buffer;
> - --tmp->SCp.buffers_residual;
> - tmp->SCp.this_residual = tmp->SCp.buffer->length;
> - tmp->SCp.ptr = sg_virt(tmp->SCp.buffer);
> - }
> + advance_sg_buffer(tmp);
>
> count = sun3scsi_dma_xfer_len(hostdata, tmp);
>

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