4.4-stable review patch. If anyone has any objections, please let me know.
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From: Finn Thain fthain@telegraphics.com.au
[ Upstream commit fd47d919d0c336e7c22862b51ee94927ffea227a ]
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: 6fe07aaffbf0 ("[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 Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/scsi/esp_scsi.c | 1 + drivers/scsi/esp_scsi.h | 2 ++ drivers/scsi/mac_esp.c | 2 ++ 3 files changed, 5 insertions(+)
--- a/drivers/scsi/esp_scsi.c +++ b/drivers/scsi/esp_scsi.c @@ -1349,6 +1349,7 @@ static int esp_data_bytes_sent(struct es
bytes_sent = esp->data_dma_len; bytes_sent -= ecount; + bytes_sent -= esp->send_cmd_residual;
/* * The am53c974 has a DMA 'pecularity'. The doc states: --- a/drivers/scsi/esp_scsi.h +++ b/drivers/scsi/esp_scsi.h @@ -540,6 +540,8 @@ struct esp {
void *dma; int dmarev; + + u32 send_cmd_residual; };
/* A front-end driver for the ESP chip should do the following in --- a/drivers/scsi/mac_esp.c +++ b/drivers/scsi/mac_esp.c @@ -426,6 +426,8 @@ static void mac_esp_send_pio_cmd(struct scsi_esp_cmd(esp, ESP_CMD_TI); } } + + esp->send_cmd_residual = esp_count; }
static int mac_esp_irq_pending(struct esp *esp)