Commit fd47d919 authored Oct 16, 2018 by Finn Thain Committed by Martin K. Petersen Oct 17, 2018

scsi: esp_scsi: Track residual for PIO transfers



If a target disconnects during a PIO data transfer the command may fail
when the target reconnects:

scsi host1: DMA length is zero!
scsi host1: cur adr[04380000] len[00000000]

The scsi bus is then reset. This happens because the residual reached
zero before the transfer was completed.

The usual residual calculation relies on the Transfer Count registers.
That works for DMA transfers but not for PIO transfers. Fix the problem
by storing the PIO transfer residual and using that to correctly
calculate bytes_sent.

Fixes: 6fe07aaf ("[SCSI] m68k: new mac_esp scsi driver")
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

parent b7ded0e8

drivers/scsi/esp_scsi.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -1352,6 +1352,7 @@ static int esp_data_bytes_sent(struct esp esp, struct esp_cmd_entry ent,

		bytes_sent = esp->data_dma_len;
		bytes_sent -= ecount;
		bytes_sent -= esp->send_cmd_residual;

		/*
		* The am53c974 has a DMA 'pecularity'. The doc states:

drivers/scsi/esp_scsi.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -524,6 +524,8 @@ struct esp {

		void *dma;
		int dmarev;

		u32 send_cmd_residual;
		};

		/* A front-end driver for the ESP chip should do the following in

drivers/scsi/mac_esp.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -394,6 +394,8 @@ static void mac_esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
		scsi_esp_cmd(esp, ESP_CMD_TI);
		}
		}

		esp->send_cmd_residual = esp_count;
		}

		static int mac_esp_irq_pending(struct esp *esp)

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