[U-Boot] [PATCH] blk: Remove various places that do flush cache after read

[Stefan Roese <sr@denx.de>]

On 22.08.2017 05:46, Bin Meng wrote:
> All these places seem to inherit the codes from the MMC driver where
> a FIXME was put in the comment. However the correct operation after
> read should be cache invalidate, not flush.
> 
> The underlying drivers should be responsible for the cache operation.
> Remove these codes completely.
> 
> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
> ---
> 
>   arch/arm/cpu/armv8/fsl-layerscape/ppa.c | 15 ---------------
>   board/toradex/common/tdx-cfg-block.c    |  2 --
>   cmd/mmc.c                               |  2 --
>   drivers/block/blk-uclass.c              |  3 ---
>   drivers/block/blk_legacy.c              |  3 ---
>   drivers/net/fm/fm.c                     |  2 --
>   drivers/net/phy/cortina.c               |  2 --
>   drivers/qe/qe.c                         |  2 --
>   8 files changed, 31 deletions(-)
> 
> diff --git a/arch/arm/cpu/armv8/fsl-layerscape/ppa.c b/arch/arm/cpu/armv8/fsl-layerscape/ppa.c
> index 24ddb5d..bbf8bba 100644
> --- a/arch/arm/cpu/armv8/fsl-layerscape/ppa.c
> +++ b/arch/arm/cpu/armv8/fsl-layerscape/ppa.c
> @@ -107,9 +107,6 @@ int ppa_init(void)
>   		return -EIO;
>   	}
>   
> -	/* flush cache after read */
> -	flush_cache((ulong)fitp, cnt * 512);
> -
>   	ret = fdt_check_header(fitp);
>   	if (ret) {
>   		free(fitp);
> @@ -134,9 +131,6 @@ int ppa_init(void)
>   	}
>   	debug("Read PPA header to 0x%p\n", ppa_hdr_ddr);
>   
> -	/* flush cache after read */
> -	flush_cache((ulong)ppa_hdr_ddr, cnt * 512);
> -
>   	ppa_esbc_hdr = (uintptr_t)ppa_hdr_ddr;
>   #endif
>   
> @@ -164,9 +158,6 @@ int ppa_init(void)
>   		return -EIO;
>   	}
>   
> -	/* flush cache after read */
> -	flush_cache((ulong)ppa_fit_addr, cnt * 512);
> -
>   #elif defined(CONFIG_SYS_LS_PPA_FW_IN_NAND)
>   	struct fdt_header fit;
>   
> @@ -208,9 +199,6 @@ int ppa_init(void)
>   	}
>   	debug("Read PPA header to 0x%p\n", ppa_hdr_ddr);
>   
> -	/* flush cache after read */
> -	flush_cache((ulong)ppa_hdr_ddr, fw_length);
> -
>   	ppa_esbc_hdr = (uintptr_t)ppa_hdr_ddr;
>   #endif
>   
> @@ -232,9 +220,6 @@ int ppa_init(void)
>   		       CONFIG_SYS_LS_PPA_FW_ADDR);
>   		return -EIO;
>   	}
> -
> -	/* flush cache after read */
> -	flush_cache((ulong)ppa_fit_addr, fw_length);
>   #else
>   #error "No CONFIG_SYS_LS_PPA_FW_IN_xxx defined"
>   #endif
> diff --git a/board/toradex/common/tdx-cfg-block.c b/board/toradex/common/tdx-cfg-block.c
> index 328c4c0..f850a3c 100644
> --- a/board/toradex/common/tdx-cfg-block.c
> +++ b/board/toradex/common/tdx-cfg-block.c
> @@ -129,8 +129,6 @@ static int tdx_cfg_block_mmc_storage(u8 *config_block, int write)
>   			ret = -EIO;
>   			goto out;
>   		}
> -		/* Flush cache after read */
> -		flush_cache((ulong)(unsigned char *)config_block, 512);
>   	} else {
>   		/* Just writing one 512 byte block */
>   		if (blk_dwrite(mmc_get_blk_desc(mmc), blk_start, 1,
> diff --git a/cmd/mmc.c b/cmd/mmc.c
> index 00697fc..5def4ea 100644
> --- a/cmd/mmc.c
> +++ b/cmd/mmc.c
> @@ -293,8 +293,6 @@ static int do_mmc_read(cmd_tbl_t *cmdtp, int flag,
>   	       curr_device, blk, cnt);
>   
>   	n = blk_dread(mmc_get_blk_desc(mmc), blk, cnt, addr);
> -	/* flush cache after read */
> -	flush_cache((ulong)addr, cnt * 512); /* FIXME */
>   	printf("%d blocks read: %s\n", n, (n == cnt) ? "OK" : "ERROR");
>   
>   	return (n == cnt) ? CMD_RET_SUCCESS : CMD_RET_FAILURE;
> diff --git a/drivers/block/blk-uclass.c b/drivers/block/blk-uclass.c
> index 3aec569..e5f00dc 100644
> --- a/drivers/block/blk-uclass.c
> +++ b/drivers/block/blk-uclass.c
> @@ -294,9 +294,6 @@ ulong blk_read_devnum(enum if_type if_type, int devnum, lbaint_t start,
>   	if (IS_ERR_VALUE(n))
>   		return n;
>   
> -	/* flush cache after read */
> -	flush_cache((ulong)buffer, blkcnt * desc->blksz);
> -
>   	return n;
>   }
>   
> diff --git a/drivers/block/blk_legacy.c b/drivers/block/blk_legacy.c
> index 981872e..16d3bfe 100644
> --- a/drivers/block/blk_legacy.c
> +++ b/drivers/block/blk_legacy.c
> @@ -232,9 +232,6 @@ ulong blk_read_devnum(enum if_type if_type, int devnum, lbaint_t start,
>   	if (IS_ERR_VALUE(n))
>   		return n;
>   
> -	/* flush cache after read */
> -	flush_cache((ulong)buffer, blkcnt * desc->blksz);
> -
>   	return n;
>   }
>   
> diff --git a/drivers/net/fm/fm.c b/drivers/net/fm/fm.c
> index 451dfde..261f1b9 100644
> --- a/drivers/net/fm/fm.c
> +++ b/drivers/net/fm/fm.c
> @@ -405,8 +405,6 @@ int fm_init_common(int index, struct ccsr_fman *reg)
>   		mmc_init(mmc);
>   		(void)mmc->block_dev.block_read(&mmc->block_dev, blk, cnt,
>   						addr);
> -		/* flush cache after read */
> -		flush_cache((ulong)addr, cnt * 512);
>   	}
>   #elif defined(CONFIG_SYS_QE_FMAN_FW_IN_REMOTE)
>   	void *addr = (void *)CONFIG_SYS_FMAN_FW_ADDR;
> diff --git a/drivers/net/phy/cortina.c b/drivers/net/phy/cortina.c
> index e0e9ed9..637d89a 100644
> --- a/drivers/net/phy/cortina.c
> +++ b/drivers/net/phy/cortina.c
> @@ -177,8 +177,6 @@ void cs4340_upload_firmware(struct phy_device *phydev)
>   		mmc_init(mmc);
>   		(void)mmc->block_dev.block_read(&mmc->block_dev, blk, cnt,
>   						addr);
> -		/* flush cache after read */
> -		flush_cache((ulong)addr, cnt * 512);
>   	}
>   #endif
>   
> diff --git a/drivers/qe/qe.c b/drivers/qe/qe.c
> index 24e764d..931c9d9 100644
> --- a/drivers/qe/qe.c
> +++ b/drivers/qe/qe.c
> @@ -221,8 +221,6 @@ void u_qe_init(void)
>   		mmc_init(mmc);
>   		(void)mmc->block_dev.block_read(&mmc->block_dev, blk, cnt,
>   						addr);
> -		/* flush cache after read */
> -		flush_cache((ulong)addr, cnt * 512);
>   	}
>   #endif
>   	u_qe_upload_firmware(addr);
> 

Did you experience any problems with the "incorrect" code in the
MMC driver?

Without looking into the underlying driver, your explanation makes
perfect sense and flushing is wrong after a read of course. So:

Reviewed-by: Stefan Roese <sr@denx.de>

Thanks,
Stefan