forked from luck/tmp_suning_uos_patched
93dce3a643
As claimed by the programmer datasheet and confirmed by the IP designer, the Block Transfer Size (BTSIZE) bitfield of the Channel x Control A Register (CTRLAx) always refers to a number of Source Width (SRC_WIDTH) transfers. Both the SRC_WIDTH and BTSIZE bitfields can be extacted from the CTRLAx register to compute the DMA residue. So the 'tx_width' field is useless and can be removed from the struct at_desc. Before this patch, atc_prep_slave_sg() was not consistent: BTSIZE was correctly initialized according to the SRC_WIDTH but 'tx_width' was always set to reg_width, which was incorrect for MEM_TO_DEV transfers. It led to bad DMA residue when 'tx_width' != SRC_WIDTH. Also the 'tx_width' field was mostly set only in the first and last descriptors. Depending on the kind of DMA transfer, this field remained uninitialized for intermediate descriptors. The accurate DMA residue was computed only when the currently processed descriptor was the first or the last of the chain. This algorithm was a little bit odd. An accurate DMA residue can always be computed using the SRC_WIDTH and BTSIZE bitfields in the CTRLAx register. Finally, the test to check whether the currently processed descriptor is the last of the chain was wrong: for cyclic transfer, last_desc->lli.dscr is NOT equal to zero, since set_desc_eol() is never called, but logically equal to first_desc->txd.phys. This bug has a side effect on the drivers/tty/serial/atmel_serial.c driver, which uses cyclic DMA transfer to receive data. Since the DMA residue was wrong each time the DMA transfer reaches the second (and last) period of the transfer, no more data were received by the USART driver till the cyclic DMA transfer loops back to the first period. Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com> Acked-by: Torsten Fleischer <torfl6749@gmail.com> Tested-by: Jirí Prchal <jiri.prchal@aksignal.cz> Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com> Signed-off-by: Vinod Koul <vinod.koul@intel.com> |
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| .. | ||
| bestcomm | ||
| dw | ||
| hsu | ||
| ioat | ||
| ipu | ||
| ppc4xx | ||
| sh | ||
| xilinx | ||
| acpi-dma.c | ||
| amba-pl08x.c | ||
| at_hdmac_regs.h | ||
| at_hdmac.c | ||
| at_xdmac.c | ||
| bcm2835-dma.c | ||
| coh901318_lli.c | ||
| coh901318.c | ||
| coh901318.h | ||
| cppi41.c | ||
| dma-jz4740.c | ||
| dma-jz4780.c | ||
| dmaengine.c | ||
| dmaengine.h | ||
| dmatest.c | ||
| edma.c | ||
| ep93xx_dma.c | ||
| fsl_raid.c | ||
| fsl_raid.h | ||
| fsl-edma.c | ||
| fsldma.c | ||
| fsldma.h | ||
| img-mdc-dma.c | ||
| imx-dma.c | ||
| imx-sdma.c | ||
| iop-adma.c | ||
| k3dma.c | ||
| Kconfig | ||
| Makefile | ||
| mic_x100_dma.c | ||
| mic_x100_dma.h | ||
| mmp_pdma.c | ||
| mmp_tdma.c | ||
| moxart-dma.c | ||
| mpc512x_dma.c | ||
| mv_xor.c | ||
| mv_xor.h | ||
| mxs-dma.c | ||
| nbpfaxi.c | ||
| of-dma.c | ||
| omap-dma.c | ||
| pch_dma.c | ||
| pl330.c | ||
| pxa_dma.c | ||
| qcom_bam_dma.c | ||
| s3c24xx-dma.c | ||
| sa11x0-dma.c | ||
| sirf-dma.c | ||
| ste_dma40_ll.c | ||
| ste_dma40_ll.h | ||
| ste_dma40.c | ||
| sun6i-dma.c | ||
| tegra20-apb-dma.c | ||
| ti-dma-crossbar.c | ||
| timb_dma.c | ||
| TODO | ||
| txx9dmac.c | ||
| txx9dmac.h | ||
| virt-dma.c | ||
| virt-dma.h | ||
| xgene-dma.c | ||