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

[Y.b. Lu]

cmd/mmc.c

Maybe SD controller on some vendor platforms doesn't support SNOOP.
flush_cache() is required to sync between DDR and cache.
Should be careful to remove this.


> -----Original Message-----
> From: Qiang Zhao
> Sent: Wednesday, August 23, 2017 11:14 AM
> To: Y.b. Lu; York Sun; Bin Meng; Grygorii Strashko; Michal Simek; Angelo
> Dureghello; Kever Yang; Jaehoon Chung; Albert Aribaud; Marcel Ziswiler;
> Markus Niebel; Z.q. Hou; Sumit Garg; Joe Hershberger; Stefan Roese;
> Wenbin Song; Simon Glass; Max Krummenacher; Masahiro Yamada; Tomas Melin;
> Q.y. Gong; Tom Rini; U-Boot Mailing List
> Subject: RE: [PATCH] blk: Remove various places that do flush cache after
> read
> 
> +Yangbo
> 
> Best Regards
> Qiang Zhao
> 
> > -----Original Message-----
> > From: York Sun
> > Sent: Wednesday, August 23, 2017 12:49 AM
> > To: Bin Meng <bmeng.cn at gmail.com>; Grygorii Strashko
> > <grygorii.strashko at ti.com>; Michal Simek <michal.simek at xilinx.com>;
> > Angelo Dureghello <angelo at sysam.it>; Kever Yang
> > <kever.yang at rock-chips.com>; Jaehoon Chung <jh80.chung at samsung.com>;
> > Albert Aribaud <albert.u.boot at aribaud.net>; Marcel Ziswiler
> > <marcel.ziswiler at toradex.com>; Markus Niebel
> > <Markus.Niebel at tq-group.com>; Z.q. Hou <zhiqiang.hou at nxp.com>; Sumit
> > Garg <sumit.garg at nxp.com>; Joe Hershberger <joe.hershberger at ni.com>;
> > Stefan Roese <sr at denx.de>; Wenbin Song <wenbin.song at nxp.com>; Qiang
> > Zhao <qiang.zhao at nxp.com>; Simon Glass <sjg at chromium.org>; Max
> > Krummenacher <max.krummenacher at toradex.com>; Masahiro Yamada
> > <yamada.masahiro at socionext.com>; Tomas Melin
> > <tomas.melin at vaisala.com>; Q.y. Gong <qianyu.gong at nxp.com>; Tom Rini
> > <trini at konsulko.com>; U-Boot Mailing List <u-boot at lists.denx.de>
> > Subject: Re: [PATCH] blk: Remove various places that do flush cache
> > after read
> >
> > On 08/21/2017 08:42 PM, 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 at 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);
> > > -
> >
> > NACK here.
> >
> >
> > >   	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
> >
> > Hold on for ppa.c. We need to flush the cache after reading PPA image
> > and it header after loading. These images need to be flushed into main
> > memory. I will need to confirm with our team if we can remove flushing
> here.
> >
> > York