Merge branch 'nicer_dma_switch' into 'master'

Reduce foot print of cycle1 -> cycle2 dma size change for fast adcs.

See merge request cds/advligorts!298

src/include/drv/iop_adc_functions.c

@@ -443,7 +443,7 @@ iop_adc_read( adcInfo_t* adcinfo, int cpuClk[] )
             *packedData = DUMMY_ADC_VAL;
             if ( first_adc_read )
             {
-                plx9056_adc_dma_setup(card,
+                plx9056_adc_dma_set_size(card,
                           cdsPciModules.adcChannels[ card ] * UNDERSAMPLE * 4 );
             }
             plx9056_adc_dma_start( card );

src/include/drv/plx_9056.c

@@ -81,6 +81,17 @@ plx9056_adc_dma_setup( int module, int dma_bytes )
     adcDma[ module ]->DMA0_DESC = PLX_DMA_TO_PCI;
 }
 
+// *****************************************************************************
+/// \brief Function changes the DMA size of an existing DMA setup
+/// called between cycle 1 and cycle 2 for fast ADCs
+///     @param[in] module ID of ADC board
+///     @param[in] new size for the DMA xfer in number of bytes
+void
+plx9056_adc_dma_set_size( int module, int dma_bytes )
+{
+    adcDma[ module ]->DMA0_BTC = dma_bytes;
+}
+
 // *****************************************************************************
 /// \brief Function sets up starts Demand DMA for ADC modules.
 /// Called once on startup.