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([2001:df0:0:200c:cd5b:7c57:228c:7f0a]) by smtp.gmail.com with ESMTPSA id i3sm15448121pfa.175.2019.06.11.16.47.58 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 11 Jun 2019 16:48:05 -0700 (PDT) Subject: Re: [PATCH] NCR5380: Support chained sg lists To: Finn Thain , "James E.J. Bottomley" , "Martin K. Petersen" Cc: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org References: <739c214bafcb9af3f6d5037cc03f57f692966675.1560223509.git.fthain@telegraphics.com.au> From: Michael Schmitz Message-ID: Date: Wed, 12 Jun 2019 11:47:56 +1200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <739c214bafcb9af3f6d5037cc03f57f692966675.1560223509.git.fthain@telegraphics.com.au> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > Signed-off-by: Finn Thain Reviewed-by: Michael Schmitz > --- > 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); >