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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Suraj Gupta , Marek Vasut , Tomi Valkeinen , Alex Bereza , Folker Schwesinger , dmaengine@vger.kernel.org, netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, git@amd.com Subject: Re: [PATCH V6 1/4] dmaengine: xilinx_dma: Fix MCDMA descriptor fields based on DMA direction Message-ID: References: <20260818174151.1608971-1-srinivas.neeli@amd.com> <20260818174151.1608971-2-srinivas.neeli@amd.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260818174151.1608971-2-srinivas.neeli@amd.com> X-ClientProxiedBy: PH8PR07CA0048.namprd07.prod.outlook.com (2603:10b6:510:2cf::19) To DU4PR04MB11791.eurprd04.prod.outlook.com (2603:10a6:10:623::11) Precedence: bulk X-Mailing-List: dmaengine@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DU4PR04MB11791:EE_|PAXPR04MB8256:EE_ X-MS-Office365-Filtering-Correlation-Id: 6fb4a873-5aa5-4980-fecb-08defd5a8761 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|19092799006|7416014|376014|23010399003|366016|56012099006|4143699003|10067099003|11063799006|18002099003|22082099003; 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This led to incorrect > residue calculations when the hardware updates direction-specific fields. > > Refactor the descriptor structure to use unions with direction-specific > field mappings, and update the residue calculation logic to select the > correct status field based on DMA direction. > > This matches the hardware descriptor layout and fixes incorrect > residue reporting. > > Fixes: 6ccd692bfb7f ("dmaengine: xilinx_dma: Add Xilinx AXI MCDMA Engine driver support") > Reviewed-by: Radhey Shyam Pandey > Signed-off-by: Srinivas Neeli > --- Reviewed-by: Frank Li > Changes in V6: > - No change. > > Changes in V5: > - No change. > > Changes in V4: > - Added Reviewed-by: Radhey Shyam Pandey. > > Changes in V3: > - Renamed subject from "for MM2S vs S2MM" to "based on DMA direction". > - Reworded commit message for clarity. > - Added XILINX_MCDMA_BD_HW_SIZE macro and static_assert to verify > descriptor size at compile time. > - Refactored residue calculation to separate addition and subtraction > operations for better readability. > > Changes in V2: > - No change. > --- > drivers/dma/xilinx/xilinx_dma.c | 26 +++++++++++++++++++------- > 1 file changed, 19 insertions(+), 7 deletions(-) > > diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c > index bef2b031dba1..2319101be778 100644 > --- a/drivers/dma/xilinx/xilinx_dma.c > +++ b/drivers/dma/xilinx/xilinx_dma.c > @@ -223,6 +223,7 @@ > #define XILINX_MCDMA_IRQ_ERR_MASK BIT(7) > #define XILINX_MCDMA_BD_EOP BIT(30) > #define XILINX_MCDMA_BD_SOP BIT(31) > +#define XILINX_MCDMA_BD_HW_SIZE 64 > > /** > * struct xilinx_vdma_desc_hw - Hardware Descriptor > @@ -277,8 +278,10 @@ struct xilinx_axidma_desc_hw { > * @buf_addr_msb: MSB of Buffer address @0x0C > * @rsvd: Reserved field @0x10 > * @control: Control Information field @0x14 > - * @status: Status field @0x18 > - * @sideband_status: Status of sideband signals @0x1C > + * @mm2s_ctrl_sideband: Sideband control info for mm2s @0x18 > + * @s2mm_status: Status field for s2mm @0x18 > + * @mm2s_status: Status field for mm2s @0x1C > + * @s2mm_sideband_status: Sideband status for s2mm @0x1C > * @app: APP Fields @0x20 - 0x30 > */ > struct xilinx_aximcdma_desc_hw { > @@ -288,10 +291,17 @@ struct xilinx_aximcdma_desc_hw { > u32 buf_addr_msb; > u32 rsvd; > u32 control; > - u32 status; > - u32 sideband_status; > + union { > + u32 mm2s_ctrl_sideband; > + u32 s2mm_status; > + }; > + union { > + u32 mm2s_status; > + u32 s2mm_sideband_status; > + }; > u32 app[XILINX_DMA_NUM_APP_WORDS]; > } __aligned(64); > +static_assert(sizeof(struct xilinx_aximcdma_desc_hw) == XILINX_MCDMA_BD_HW_SIZE); > > /** > * struct xilinx_cdma_desc_hw - Hardware Descriptor > @@ -1015,9 +1025,11 @@ static u32 xilinx_dma_get_residue(struct xilinx_dma_chan *chan, > struct xilinx_aximcdma_tx_segment, > node); > aximcdma_hw = &aximcdma_seg->hw; > - residue += > - (aximcdma_hw->control & chan->xdev->max_buffer_len) - > - (aximcdma_hw->status & chan->xdev->max_buffer_len); > + residue += aximcdma_hw->control & chan->xdev->max_buffer_len; > + if (chan->direction == DMA_DEV_TO_MEM) > + residue -= aximcdma_hw->s2mm_status & chan->xdev->max_buffer_len; > + else > + residue -= aximcdma_hw->mm2s_status & chan->xdev->max_buffer_len; > } > } > > -- > 2.43.0 >