diff options
| -rw-r--r-- | Documentation/scsi/scsi_mid_low_api.rst | 67 |
1 files changed, 18 insertions, 49 deletions
diff --git a/Documentation/scsi/scsi_mid_low_api.rst b/Documentation/scsi/scsi_mid_low_api.rst index 9d15e20b0b5e..3cd6dce98e74 100644 --- a/Documentation/scsi/scsi_mid_low_api.rst +++ b/Documentation/scsi/scsi_mid_low_api.rst @@ -683,11 +683,7 @@ Details:: * * Calling context: kernel thread * - * Notes: If 'no_async_abort' is defined this callback - * will be invoked from scsi_eh thread. No other commands - * will then be queued on current host during eh. - * Otherwise it will be called whenever scsi_timeout() - * is called due to a command timeout. + * Notes: This is called only for a command that has timed out. * * Optionally defined in: LLD **/ @@ -990,7 +986,7 @@ struct scsi_host_template There is one "struct scsi_host_template" instance per LLD [#]_. It is typically initialized as a file scope static in a driver's header file. That way members that are not explicitly initialized will be set to 0 or NULL. -Member of interest: +Members of interest: name - name of driver (may contain spaces, please limit to @@ -1006,6 +1002,13 @@ Member of interest: - primary callback that the mid level uses to inject SCSI commands into an LLD. + vendor_id + - a unique value that identifies the vendor supplying + the LLD for the Scsi_Host. Used most often in validating + vendor-specific message requests. Value consists of an + identifier type and a vendor-specific value. + See scsi_netlink.h for a description of valid formats. + The structure is defined and commented in include/scsi/scsi_host.h .. [#] In extreme situations a single driver may have several instances @@ -1046,9 +1049,6 @@ of interest: - maximum number of commands that can be queued on devices controlled by the host. Overridden by LLD calls to scsi_change_queue_depth(). - no_async_abort - - 1=>Asynchronous aborts are not supported - - 0=>Timed-out commands will be aborted asynchronously hostt - pointer to driver's struct scsi_host_template from which this struct Scsi_Host instance was spawned @@ -1057,22 +1057,10 @@ of interest: transportt - pointer to driver's struct scsi_transport_template instance (if any). FC and SPI transports currently supported. - sh_list - - a double linked list of pointers to all struct Scsi_Host - instances (currently ordered by ascending host_no) - my_devices - - a double linked list of pointers to struct scsi_device - instances that belong to this host. hostdata[0] - area reserved for LLD at end of struct Scsi_Host. Size - is set by the second argument (named 'xtr_bytes') to + is set by the second argument (named 'privsize') to scsi_host_alloc(). - vendor_id - - a unique value that identifies the vendor supplying - the LLD for the Scsi_Host. Used most often in validating - vendor-specific message requests. Value consists of an - identifier type and a vendor-specific value. - See scsi_netlink.h for a description of valid formats. The scsi_host structure is defined in include/scsi/scsi_host.h @@ -1094,30 +1082,11 @@ Members of interest: cmnd - array containing SCSI command - cmnd_len + cmd_len - length (in bytes) of SCSI command sc_data_direction - direction of data transfer in data phase. See "enum dma_data_direction" in include/linux/dma-mapping.h - request_bufflen - - number of data bytes to transfer (0 if no data phase) - use_sg - - ==0 -> no scatter gather list, hence transfer data - to/from request_buffer - - >0 -> scatter gather list (actually an array) in - request_buffer with use_sg elements - request_buffer - - either contains data buffer or scatter gather list - depending on the setting of use_sg. Scatter gather - elements are defined by 'struct scatterlist' found - in include/linux/scatterlist.h . - done - - function pointer that should be invoked by LLD when the - SCSI command is completed (successfully or otherwise). - Should only be called by an LLD if the LLD has accepted - the command (i.e. queuecommand() returned or will return - 0). The LLD may invoke 'done' prior to queuecommand() - finishing. result - should be set by LLD prior to calling 'done'. A value of 0 implies a successfully completed command (and all @@ -1140,13 +1109,13 @@ Members of interest: device - pointer to scsi_device object that this command is associated with. - resid + resid_len (access by calling scsi_set_resid() / scsi_get_resid()) - an LLD should set this unsigned integer to the requested transfer length (i.e. 'request_bufflen') less the number - of bytes that are actually transferred. 'resid' is + of bytes that are actually transferred. 'resid_len' is preset to 0 so an LLD can ignore it if it cannot detect underruns (overruns should not be reported). An LLD - should set 'resid' prior to invoking 'done'. The most + should set 'resid_len' prior to invoking 'done'. The most interesting case is data transfers from a SCSI target device (e.g. READs) that underrun. underflow @@ -1155,10 +1124,10 @@ Members of interest: figure. Not many LLDs implement this check and some that do just output an error message to the log rather than report a DID_ERROR. Better for an LLD to implement - 'resid'. + 'resid_len'. -It is recommended that a LLD set 'resid' on data transfers from a SCSI -target device (e.g. READs). It is especially important that 'resid' is set +It is recommended that a LLD set 'resid_len' on data transfers from a SCSI +target device (e.g. READs). It is especially important that 'resid_len' is set when such data transfers have sense keys of MEDIUM ERROR and HARDWARE ERROR (and possibly RECOVERED ERROR). In these cases if a LLD is in doubt how much data has been received then the safest approach is to indicate no bytes have @@ -1168,7 +1137,7 @@ a LLD might use these helpers:: scsi_set_resid(SCpnt, scsi_bufflen(SCpnt)); where 'SCpnt' is a pointer to a scsi_cmnd object. To indicate only three 512 -bytes blocks has been received 'resid' could be set like this:: +bytes blocks have been received 'resid_len' could be set like this:: scsi_set_resid(SCpnt, scsi_bufflen(SCpnt) - (3 * 512)); |