Re: [Qemu-arm] [PATCH 2/2] block: m25p80: Introduce Die Erase command

["Edgar E. Iglesias" <edgar.iglesias@gmail.com>]

On Mon, Dec 19, 2016 at 06:21:13AM +0000, Krzeminski, Marcin (Nokia - PL/Wroclaw) wrote:
> 
> 
> > -----Original Message-----
> > From: Edgar E. Iglesias [mailto:edgar.iglesias@gmail.com]
> > Sent: Friday, December 16, 2016 5:36 PM
> > To: Krzeminski, Marcin (Nokia - PL/Wroclaw)
> > <marcin.krzeminski@nokia.com>
> > Cc: qemu-devel@nongnu.org; peter.maydell@linaro.org; rfsw-
> > patches@mlist.nokia.com; qemu-arm@nongnu.org; clg@kaod.org
> > Subject: Re: [Qemu-arm] [PATCH 2/2] block: m25p80: Introduce Die Erase
> > command
> > 
> > On Fri, Dec 16, 2016 at 02:27:42PM +0100, marcin.krzeminski@nokia.com
> > wrote:
> > > From: Marcin Krzeminski <marcin.krzeminski@nokia.com>
> > >
> > > Big flash chips (like mt25qu01g) are consisted from dies.
> > > Because of that some manufactures remove support for Chip Erase giving
> > > Die Erase command instead.To avoid unnecessary code complication,
> > > support for chip erase for mt25qu01g is not removed.
> > >
> > > Signed-off-by: Marcin Krzeminski <marcin.krzeminski@nokia.com>
> > > ---
> > >  hw/block/m25p80.c | 33 +++++++++++++++++++++++++++++----
> > >  1 file changed, 29 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/hw/block/m25p80.c b/hw/block/m25p80.c index
> > > 2bc7028..0bc1fbf 100644
> > > --- a/hw/block/m25p80.c
> > > +++ b/hw/block/m25p80.c
> > > @@ -216,8 +216,8 @@ static const FlashPartInfo known_devices[] = {
> > >      { INFO("n25q128",     0x20ba18,      0,  64 << 10, 256, 0) },
> > >      { INFO("n25q256a",    0x20ba19,      0,  64 << 10, 512, ER_4K) },
> > >      { INFO("n25q512a",    0x20ba20,      0,  64 << 10, 1024, ER_4K) },
> > > -    { INFO("mt25ql01g",   0x20ba21,      0,  64 << 10, 2048, ER_4K) },
> > > -    { INFO("mt25qu01g",   0x20bb21,      0,  64 << 10, 2048, ER_4K) },
> > > +    { INFO("mt25ql01g",   0x20ba21, 0x1040,  64 << 10, 2048, ER_4K) },
> > > +    { INFO("mt25qu01g",   0x20bb21, 0x1040,  64 << 10, 2048, ER_4K) },
> > >
> > >      /* Spansion -- single (large) sector size only, at least
> > >       * for the chips listed here (without boot sectors).
> > > @@ -358,6 +358,8 @@ typedef enum {
> > >
> > >      REVCR = 0x65,
> > >      WEVCR = 0x61,
> > > +
> > > +    DIE_ERASE = 0xC4,
> > >  } FlashCMD;
> > >
> > >  typedef enum {
> > > @@ -411,6 +413,7 @@ typedef struct Flash {
> > >      bool reset_enable;
> > >      bool quad_enable;
> > >      uint8_t ear;
> > > +    uint32_t die_cnt;
> > >
> > >      int64_t dirty_page;
> > >
> > > @@ -492,7 +495,7 @@ static inline void flash_sync_area(Flash *s,
> > > int64_t off, int64_t len)
> > >
> > >  static void flash_erase(Flash *s, int offset, FlashCMD cmd)  {
> > > -    uint32_t len;
> > > +    uint32_t len = 0;
> > 
> > Do you really need this?
> 
> Compilation warning.

Of course, because you are logging len in a code path that
doesn't use the variable.

Let me be more clear below:

> > 
> > >      uint8_t capa_to_assert = 0;
> > >
> > >      switch (cmd) {
> > > @@ -513,6 +516,16 @@ static void flash_erase(Flash *s, int offset,
> > FlashCMD cmd)
> > >      case BULK_ERASE:
> > >          len = s->size;
> > >          break;
> > > +    case DIE_ERASE:
> > > +        if (s->die_cnt) {
> > > +            len = s->size / s->die_cnt;
> > > +            offset = offset & (~(len-1));
> > > +        } else {
> > > +            qemu_log_mask(LOG_GUEST_ERROR, "M25P80: %d die erase not
> > supported by"
> > > +                          " device\n", len);

Don't log len here...



> > > +            return;
> > > +        }
> > > +        break;
> > >      default:
> > >          abort();
> > >      }
> > > @@ -634,6 +647,7 @@ static void complete_collecting_data(Flash *s)
> > >      case ERASE4_32K:
> > >      case ERASE_SECTOR:
> > >      case ERASE4_SECTOR:
> > > +    case DIE_ERASE:
> > >          flash_erase(s, s->cur_addr, s->cmd_in_progress);
> > >          break;
> > >      case WRSR:
> > > @@ -684,6 +698,7 @@ static void reset_memory(Flash *s)
> > >      s->write_enable = false;
> > >      s->reset_enable = false;
> > >      s->quad_enable = false;
> > > +    s->die_cnt = 0;
> > >
> > >      switch (get_man(s)) {
> > >      case MAN_NUMONYX:
> > > @@ -716,7 +731,15 @@ static void reset_memory(Flash *s)
> > >              s->four_bytes_address_mode = true;
> > >          }
> > >          if (!(s->nonvolatile_cfg & NVCFG_LOWER_SEGMENT_MASK)) {
> > > -            s->ear = s->size / MAX_3BYTES_SIZE - 1;
> > > +            s->ear = ( s->size > MAX_3BYTES_SIZE ? s->size / MAX_3BYTES_SIZE
> > - 1 : 0);
> > > +        }
> > > +        /* 1GiB devices */
> > > +        if (s->pi->id[2] == 0x21) {
> > > +            /* MT25Q00 has 2 dies N25Q00 has 4 */
> > > +            if (s->pi->id[4] & BIT(6))
> > > +                s->die_cnt = 2;
> > > +            else
> > > +                s->die_cnt = 4;
> > 
> > Decoding of die_cnt should probably be done in realize().
> > 
> > >          }
> > >          break;
> > >      case MAN_MACRONIX:
> > > @@ -880,6 +903,7 @@ static void decode_new_cmd(Flash *s, uint32_t
> > value)
> > >      case PP:
> > >      case PP4:
> > >      case PP4_4:
> > > +    case DIE_ERASE:
> > >          s->needed_bytes = get_addr_length(s);
> > >          s->pos = 0;
> > >          s->len = 0;
> > > @@ -1217,6 +1241,7 @@ static const VMStateDescription vmstate_m25p80
> > = {
> > >          VMSTATE_UINT8(spansion_cr2nv, Flash),
> > >          VMSTATE_UINT8(spansion_cr3nv, Flash),
> > >          VMSTATE_UINT8(spansion_cr4nv, Flash),
> > > +        VMSTATE_UINT32(die_cnt, Flash),
> > 
> > die_cnt is fixed per instance. Since it doesn't change, it doesn't need to be
> > part of VMSTATE.
> 
> Yes, you are right. Even more, number of a dies is fixed attribute of chip, so it could
> Be a part of FlashPartInfo. I'll up v2.
> 
> Thanks,
> Marcin
> 
> > 
> > >          VMSTATE_END_OF_LIST()
> > >      }
> > >  };
> > > --
> > > 2.7.4
> > >
> > >