Hi Tomas, As you said, the dma_alloc_coherent should return a page address with zeroes in the lowest bits, but I have 100% confidence in that. Therefore, I try to round it up if not. Otherwise, it will lead the controller panic. The code over there is just in case. -----Original Message----- From: Tomas Henzl [mailto:thenzl@xxxxxxxxxx] Sent: Thursday, February 10, 2011 10:37 PM To: 'linux-scsi@xxxxxxxxxxxxxxx' Cc: nick.cheng@xxxxxxxxxxxx Subject: [PATCH 2/2] arcmsr: code cleanup and some corrections Hi Nick, I'm confused with what this code does, I think I must miss something. dma_coherent = dma_alloc_coherent(&pdev->dev, acb->uncache_size, &dma_coherent_handle, GFP_KERNEL); ... I think that the dma_alloc_coherent returns a page address with zeroes in the lowest bits That would mean the offset computed below is useless as the result is zero every time. Added to that is that you then increase dma_coherent_handle by the offset, while dma_coherent is increased by multiples of sizeof CommandControlBlock, at least it looks so ... offset = roundup((unsigned long)dma_coherent, 32) - (unsigned long)dma_coherent; dma_coherent_handle = dma_coherent_handle + offset; dma_coherent = (struct CommandControlBlock *)dma_coherent + offset; The patch below removes the offset computation. Signed-off-by: Tomas henzl <thenzl@xxxxxxxxxx> diff --git a/drivers/scsi/arcmsr/arcmsr_hba.c b/drivers/scsi/arcmsr/arcmsr_hba.c index 4cd522b..da93974 100644 --- a/drivers/scsi/arcmsr/arcmsr_hba.c +++ b/drivers/scsi/arcmsr/arcmsr_hba.c @@ -441,10 +441,11 @@ static int arcmsr_alloc_ccb_pool(struct AdapterControlBlock *acb) struct CommandControlBlock *ccb_tmp; int i = 0, j = 0; dma_addr_t cdb_phyaddr; - unsigned long roundup_ccbsize = 0, offset; + unsigned long roundup_ccbsize; unsigned long max_xfer_len; unsigned long max_sg_entrys; uint32_t firm_config_version; + for (i = 0; i < ARCMSR_MAX_TARGETID; i++) for (j = 0; j < ARCMSR_MAX_TARGETLUN; j++) acb->devstate[i][j] = ARECA_RAID_GONE; @@ -454,12 +455,12 @@ static int arcmsr_alloc_ccb_pool(struct AdapterControlBlock *acb) firm_config_version = acb->firm_cfg_version; if((firm_config_version & 0xFF) >= 3){ max_xfer_len = (ARCMSR_CDB_SG_PAGE_LENGTH << ((firm_config_version >> 8) & 0xFF)) * 1024;/* max 4M byte */ - max_sg_entrys = (max_xfer_len/4096); + max_sg_entrys = (max_xfer_len/4096); } acb->host->max_sectors = max_xfer_len/512; acb->host->sg_tablesize = max_sg_entrys; roundup_ccbsize = roundup(sizeof(struct CommandControlBlock) + (max_sg_entrys - 1) * sizeof(struct SG64ENTRY), 32); - acb->uncache_size = roundup_ccbsize * ARCMSR_MAX_FREECCB_NUM + 32; + acb->uncache_size = roundup_ccbsize * ARCMSR_MAX_FREECCB_NUM; dma_coherent = dma_alloc_coherent(&pdev->dev, acb->uncache_size, &dma_coherent_handle, GFP_KERNEL); if(!dma_coherent){ printk(KERN_NOTICE "arcmsr%d: dma_alloc_coherent got error \n", acb->host->host_no); @@ -468,9 +469,6 @@ static int arcmsr_alloc_ccb_pool(struct AdapterControlBlock *acb) acb->dma_coherent = dma_coherent; acb->dma_coherent_handle = dma_coherent_handle; memset(dma_coherent, 0, acb->uncache_size); - offset = roundup((unsigned long)dma_coherent, 32) - (unsigned long)dma_coherent; - dma_coherent_handle = dma_coherent_handle + offset; - dma_coherent = (struct CommandControlBlock *)dma_coherent + offset; ccb_tmp = dma_coherent; acb->vir2phy_offset = (unsigned long)dma_coherent - (unsigned long)dma_coherent_handle; for(i = 0; i < ARCMSR_MAX_FREECCB_NUM; i++){ -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
