staging: comedi: das1800: remove 'qram_len' boardinfo

The "hc" type boards have 64 analog input channels with a 64
entry queue. All the others have 16 channels and a 256 entry
queue.

EXP-1800 expansion boards can be used to increase the number
of analog inputs on the 16 channel boards, 16 channels per
EXP-1800, for a total of 256 channels.

Remove the 'qram_len' member of the boardinfo and use the
'id' member to determine the number of channels.

Add a comment about the number of channels and the unclear
mapping of the channels when EXP-1800 boards are used.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/drivers/das1800.c b/drivers/staging/comedi/drivers/das1800.c
index 32807631dec67eb6de92c7b527bf07ca96192f96..d3aca976ee4c6bc153dd38a1be22cf4aa0919328 100644 (file)
--- a/drivers/staging/comedi/drivers/das1800.c
+++ b/drivers/staging/comedi/drivers/das1800.c
@@ -226,7 +226,6 @@ struct das1800_board {
        const char *name;
        unsigned char id;
        int ai_speed;           /* max conversion period in nanoseconds */
-       int qram_len;           /* length of card's channel / gain queue */
        unsigned int is_01_series:1;
 };
 
@@ -239,116 +238,98 @@ static const struct das1800_board das1800_boards[] = {
                .name           = "das-1701st",
                .id             = DAS1800_ID_ST,
                .ai_speed       = 6250,
-               .qram_len       = 256,
                .is_01_series   = 1,
        },
        [BOARD_DAS1701ST_DA] = {
                .name           = "das-1701st-da",
                .id             = DAS1800_ID_ST_DA,
                .ai_speed       = 6250,
-               .qram_len       = 256,
                .is_01_series   = 1,
        },
        [BOARD_DAS1702ST] = {
                .name           = "das-1702st",
                .id             = DAS1800_ID_ST,
                .ai_speed       = 6250,
-               .qram_len       = 256,
        },
        [BOARD_DAS1702ST_DA] = {
                .name           = "das-1702st-da",
                .id             = DAS1800_ID_ST_DA,
                .ai_speed       = 6250,
-               .qram_len       = 256,
        },
        [BOARD_DAS1702HR] = {
                .name           = "das-1702hr",
                .id             = DAS1800_ID_HR,
                .ai_speed       = 20000,
-               .qram_len       = 256,
        },
        [BOARD_DAS1702HR_DA] = {
                .name           = "das-1702hr-da",
                .id             = DAS1800_ID_HR_DA,
                .ai_speed       = 20000,
-               .qram_len       = 256,
        },
        [BOARD_DAS1701AO] = {
                .name           = "das-1701ao",
                .id             = DAS1800_ID_AO,
                .ai_speed       = 6250,
-               .qram_len       = 256,
                .is_01_series   = 1,
        },
        [BOARD_DAS1702AO] = {
                .name           = "das-1702ao",
                .id             = DAS1800_ID_AO,
                .ai_speed       = 6250,
-               .qram_len       = 256,
        },
        [BOARD_DAS1801ST] = {
                .name           = "das-1801st",
                .id             = DAS1800_ID_ST,
                .ai_speed       = 3000,
-               .qram_len       = 256,
                .is_01_series   = 1,
        },
        [BOARD_DAS1801ST_DA] = {
                .name           = "das-1801st-da",
                .id             = DAS1800_ID_ST_DA,
                .ai_speed       = 3000,
-               .qram_len       = 256,
                .is_01_series   = 1,
        },
        [BOARD_DAS1802ST] = {
                .name           = "das-1802st",
                .id             = DAS1800_ID_ST,
                .ai_speed       = 3000,
-               .qram_len       = 256,
        },
        [BOARD_DAS1802ST_DA] = {
                .name           = "das-1802st-da",
                .id             = DAS1800_ID_ST_DA,
                .ai_speed       = 3000,
-               .qram_len       = 256,
        },
        [BOARD_DAS1802HR] = {
                .name           = "das-1802hr",
                .id             = DAS1800_ID_HR,
                .ai_speed       = 10000,
-               .qram_len       = 256,
        },
        [BOARD_DAS1802HR_DA] = {
                .name           = "das-1802hr-da",
                .id             = DAS1800_ID_HR_DA,
                .ai_speed       = 10000,
-               .qram_len       = 256,
        },
        [BOARD_DAS1801HC] = {
                .name           = "das-1801hc",
                .id             = DAS1800_ID_HC,
                .ai_speed       = 3000,
-               .qram_len       = 64,
                .is_01_series   = 1,
        },
        [BOARD_DAS1802HC] = {
                .name           = "das-1802hc",
                .id             = DAS1800_ID_HC,
                .ai_speed       = 3000,
-               .qram_len       = 64,
        },
        [BOARD_DAS1801AO] = {
                .name           = "das-1801ao",
                .id             = DAS1800_ID_AO,
                .ai_speed       = 3000,
-               .qram_len       = 256,
                .is_01_series   = 1,
        },
        [BOARD_DAS1802AO] = {
                .name           = "das-1802ao",
                .id             = DAS1800_ID_AO,
                .ai_speed       = 3000,
-               .qram_len       = 256,
        },
 };
 
@@ -1292,13 +1273,26 @@ static int das1800_attach(struct comedi_device *dev,
        if (ret)
                return ret;
 
-       /* Analog Input subdevice */
+       /*
+        * Analog Input subdevice
+        *
+        * The "hc" type boards have 64 analog input channels and a 64
+        * entry QRAM fifo.
+        *
+        * All the other board types have 16 on-board channels. Each channel
+        * can be expanded to 16 channels with the addition of an EXP-1800
+        * expansion board for a total of 256 channels. The QRAM fifo on
+        * these boards has 256 entries.
+        *
+        * From the datasheets it's not clear what the comedi channel to
+        * actual physical channel mapping is when EXP-1800 boards are used.
+        */
        s = &dev->subdevices[0];
        s->type         = COMEDI_SUBD_AI;
        s->subdev_flags = SDF_READABLE | SDF_DIFF | SDF_GROUND;
        if (board->id != DAS1800_ID_HC)
                s->subdev_flags |= SDF_COMMON;
-       s->n_chan       = board->qram_len;
+       s->n_chan       = (board->id == DAS1800_ID_HC) ? 64 : 256;
        s->maxdata      = is_16bit ? 0xffff : 0x0fff;
        s->range_table  = board->is_01_series ? &das1801_ai_range
                                              : &das1802_ai_range;