[Yaffs-archive] Re:[YAFFS] Latest CVS ==> Interaction with mtd

[Jeffrey Lim]

Hi, regarding the optimizations you wrote, how about if we optimize them
further? (or at least, to me, it looks like an optimization). I am by no
means a flash expert, or an mtd one at that, so pardon me if i do
something wrong. Correct me and i will listen. :)

Have a look at my humble optimizations, if you dont mind.. (basically an
"if"-statement optimization that shouldnt touch the logic that you coded
in)


On Sat, 23 Nov 2002 10:00:44 +0100, "Thomas Gleixner"
<tglx@linutronix.de> said:
> Charles, 
> 
> [---- snip ------]
> 
> I made following changes to yaffs_mtdif.c and improved the performance,
> due to 
> the fact, that data and oob area are read and written in one go, without 
> (de)selecting the chip again. 
> 
> RCS file: /home/aleph1/cvs/yaffs/yaffs_mtdif.c,v
> retrieving revision 1.2
> diff -u -r1.2 yaffs_mtdif.c
> --- yaffs_mtdif.c       27 Aug 2002 03:31:38 -0000      1.2
> +++ yaffs_mtdif.c       23 Nov 2002 07:54:21 -0000
> @@ -32,11 +32,12 @@
>  	
>  	__u8 *spareAsBytes = (__u8 *)spare;
>  	
> -       if(data)
> +       if(data && !spare)
>  		mtd->write(mtd,addr,YAFFS_BYTES_PER_CHUNK,&dummy,data);
> -       if(spare)
> +       if(!data && spare)
>  		mtd->write_oob(mtd,addr,YAFFS_BYTES_PER_SPARE,&dummy,spareAsBytes);
> -
> +       if(data && spare)
> +               
> mtd->write_ecc(mtd,addr,YAFFS_BYTES_PER_CHUNK,&dummy,data,spareAsBytes,NAND_OOB_NONE);
>  	return YAFFS_OK;
>  }


i was just thinking - how about the one below (pardon me for not using a
diff - i dont have ready access to a unix box right now; please check the
logic below and see if it works)

------ code --------
"@@ -32 @@"
        
        __u8 *spareAsBytes = (__u8 *)spare;
        
        if(data) {
            if(spare)
                mtd->write_ecc(mtd,addr,YAFFS_BYTES_PER_CHUNK,&dummy,data,spareAsBytes,NAND_OOB_NONE);
            else
                mtd->write(mtd,addr,YAFFS_BYTES_PER_CHUNK,&dummy,data);
        }
        else if(spare)
            mtd->write_oob(mtd,addr,YAFFS_BYTES_PER_SPARE,&dummy,spareAsBytes);

        return YAFFS_OK;
}
------ code --------


>  
> @@ -50,10 +51,12 @@
>  	
>  	__u8 *spareAsBytes = (__u8 *)spare;
>  	
> -       if(data)
> +       if(data && !spare)
>  		mtd->read(mtd,addr,YAFFS_BYTES_PER_CHUNK,&dummy,data);
> -       if(spare)
> +       if(!data && spare)
>  		mtd->read_oob(mtd,addr,YAFFS_BYTES_PER_SPARE,&dummy,spareAsBytes);
> +       if(data && spare)
> +               
> mtd->read_ecc(mtd,addr,YAFFS_BYTES_PER_CHUNK,&dummy,data,spareAsBytes,NAND_OOB_NONE);
>  
>  	return YAFFS_OK;
>  }
> 

------ code --------
"@@ -50 @@"
        
        __u8 *spareAsBytes = (__u8 *)spare;
        
        if(data) {
            if(spare)
                mtd->read_ecc(mtd,addr,YAFFS_BYTES_PER_CHUNK,&dummy,data,spareAsBytes,NAND_OOB_NONE);
            else
                mtd->read(mtd,addr,YAFFS_BYTES_PER_CHUNK,&dummy,data);
         }
         else if(spare)
                mtd->read_oob(mtd,addr,YAFFS_BYTES_PER_SPARE,&dummy,spareAsBytes);

         return YAFFS_OK;
}

------ code --------


thanks and regards
-jf

 
--
  "It's an extraordinary world!" - jfsworld <at> fastmail.fm
 
 


---------------------------------------------------------------------------------------
This mailing list is hosted by Toby Churchill open software (www.toby-churchill.org).
If mailing list membership is no longer wanted you can remove yourself from the list by 
sending an email to yaffs-request@toby-churchill.org with the text "unsubscribe" 
(without the quotes) as the subject.