staging: comedi: fix minimum AO period for NI 625x and NI 628x

commit 34b55d8c48f4f76044d8f4d6ec3dc786cf210312 upstream.

The minimum period was set to 357 ns, while the divider for these boards is 50
ns. This prevented to output at maximum speed as ni_ao_cmdtest() would return
357 but would not accept it.

Not sure why it was set to 357 ns (this was done before the git history,
which starts 5 years ago). My guess is that it comes from reading the
specification stating a 2.8 MHz rate (~ 357 ns). The latest
specification states a 2.86 MHz rate (~ 350 ns), which makes a lot
more sense.

Tested on a pci-6251.

Signed-off-by: Éric Piel <piel@delmic.com>
Acked-By: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/drivers/ni_pcimio.c b/drivers/staging/comedi/drivers/ni_pcimio.c
index f284a90720ecef0cc455c9af0918d4bd236eab87..f3f5478669e79be71e03a5f837d9e2ae1fdcfe8c 100644 (file)
--- a/drivers/staging/comedi/drivers/ni_pcimio.c
+++ b/drivers/staging/comedi/drivers/ni_pcimio.c
@@ -963,7 +963,7 @@ static const struct ni_board_struct ni_boards[] = {
         .ao_range_table = &range_ni_M_625x_ao,
         .reg_type = ni_reg_625x,
         .ao_unipolar = 0,
-        .ao_speed = 357,
+        .ao_speed = 350,
         .num_p0_dio_channels = 8,
         .caldac = {caldac_none},
         .has_8255 = 0,
@@ -982,7 +982,7 @@ static const struct ni_board_struct ni_boards[] = {
         .ao_range_table = &range_ni_M_625x_ao,
         .reg_type = ni_reg_625x,
         .ao_unipolar = 0,
-        .ao_speed = 357,
+        .ao_speed = 350,
         .num_p0_dio_channels = 8,
         .caldac = {caldac_none},
         .has_8255 = 0,
@@ -1001,7 +1001,7 @@ static const struct ni_board_struct ni_boards[] = {
         .ao_range_table = &range_ni_M_625x_ao,
         .reg_type = ni_reg_625x,
         .ao_unipolar = 0,
-        .ao_speed = 357,
+        .ao_speed = 350,
         .num_p0_dio_channels = 8,
         .caldac = {caldac_none},
         .has_8255 = 0,
@@ -1037,7 +1037,7 @@ static const struct ni_board_struct ni_boards[] = {
         .ao_range_table = &range_ni_M_625x_ao,
         .reg_type = ni_reg_625x,
         .ao_unipolar = 0,
-        .ao_speed = 357,
+        .ao_speed = 350,
         .num_p0_dio_channels = 32,
         .caldac = {caldac_none},
         .has_8255 = 0,
@@ -1056,7 +1056,7 @@ static const struct ni_board_struct ni_boards[] = {
         .ao_range_table = &range_ni_M_625x_ao,
         .reg_type = ni_reg_625x,
         .ao_unipolar = 0,
-        .ao_speed = 357,
+        .ao_speed = 350,
         .num_p0_dio_channels = 32,
         .caldac = {caldac_none},
         .has_8255 = 0,
@@ -1092,7 +1092,7 @@ static const struct ni_board_struct ni_boards[] = {
         .ao_range_table = &range_ni_M_628x_ao,
         .reg_type = ni_reg_628x,
         .ao_unipolar = 1,
-        .ao_speed = 357,
+        .ao_speed = 350,
         .num_p0_dio_channels = 8,
         .caldac = {caldac_none},
         .has_8255 = 0,
@@ -1111,7 +1111,7 @@ static const struct ni_board_struct ni_boards[] = {
         .ao_range_table = &range_ni_M_628x_ao,
         .reg_type = ni_reg_628x,
         .ao_unipolar = 1,
-        .ao_speed = 357,
+        .ao_speed = 350,
         .num_p0_dio_channels = 8,
         .caldac = {caldac_none},
         .has_8255 = 0,
@@ -1147,7 +1147,7 @@ static const struct ni_board_struct ni_boards[] = {
         .ao_range_table = &range_ni_M_628x_ao,
         .reg_type = ni_reg_628x,
         .ao_unipolar = 1,
-        .ao_speed = 357,
+        .ao_speed = 350,
         .num_p0_dio_channels = 32,
         .caldac = {caldac_none},
         .has_8255 = 0,