On 11/08/2018 04:15 PM, Boris Brezillon wrote: > On Thu, 8 Nov 2018 13:58:45 +0000 > <Tudor.Ambarus@xxxxxxxxxxxxx> wrote: > >> On 11/08/2018 02:54 PM, Boris Brezillon wrote: >>> On Thu, 8 Nov 2018 11:07:11 +0000 >>> <Tudor.Ambarus@xxxxxxxxxxxxx> wrote: >>> >>>> The map selector is limited to a maximum of 8 bits, allowing >>>> for a maximum of 256 possible map configurations. The total >>>> number of map configurations should be addressable by the >>>> total number of bits described by the detection commands. >>>> >>>> For example: if there are five to eight possible sector map >>>> configurations, at least three configuration detection commands >>>> will be needed to extract three bits of configuration selection >>>> information from the device in order to identify which configuration >>>> is currently in use. >>>> >>>> Suggested-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx> >>> >>> I don't remember suggesting this :-). >> >> I see this when you discussed with Yogesh: >> >> + for (nmaps = 0; i< smpt_len; nmaps++) { >> + if(!(smpt[i] & SMPT_DESC_TYPE_MAP)) { >> + i += 2; >> + continue; >> + } >> + >> + if(!map_id_is_valid) { >> + if (nmaps) { >> + ret = NULL; >> + break; >> + } >> >> If I understand correctly, you meant that if there are no detection commands, >> and more than a configuration map, then return an error. > > Yes, because in this case we have no way to know what config is > currently selected. > >> >> This is correct in my opinion. What I did was to generalize this idea. If smtp >> defines more maps than you can select using detection commands, return error. > > AFAICT you're no longer checking that map_id is valid (see below). > >> >> + >> + ret = smpt+i; >> + } else if (map_id == SMPT_MAP_ID(smpt[i])) { >> + ret = smpt+i; >> + break; >> + } >> + >> /* increment the table index to the next map */ >> i += SMPT_MAP_REGION_COUNT(smpt[i]) + 1; >> } >> >>> >>>> Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx> >>>> --- >>>> drivers/mtd/spi-nor/spi-nor.c | 15 +++++++++++++-- >>>> 1 file changed, 13 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c >>>> index 59dcedb08691..bd1866d714f2 100644 >>>> --- a/drivers/mtd/spi-nor/spi-nor.c >>>> +++ b/drivers/mtd/spi-nor/spi-nor.c >>>> @@ -2868,7 +2868,7 @@ static const u32 *spi_nor_get_map_in_use(struct spi_nor *nor, const u32 *smpt, >>>> const u32 *ret = NULL; >>>> u32 addr; >>>> int err; >>>> - u8 i; >>>> + u8 i, ncmds, nmaps; >>>> u8 addr_width, read_opcode, read_dummy; >>>> u8 read_data_mask, data_byte, map_id; >>>> >>>> @@ -2877,6 +2877,7 @@ static const u32 *spi_nor_get_map_in_use(struct spi_nor *nor, const u32 *smpt, >>>> read_opcode = nor->read_opcode; >>>> >>>> map_id = 0; >>>> + ncmds = 0; >>>> /* Determine if there are any optional Detection Command Descriptors */ >>>> for (i = 0; i < smpt_len; i += 2) { >>>> if (smpt[i] & SMPT_DESC_TYPE_MAP) >>>> @@ -2896,6 +2897,7 @@ static const u32 *spi_nor_get_map_in_use(struct spi_nor *nor, const u32 *smpt, >>>> * Configuration that is currently in use. >>>> */ >>>> map_id = map_id << 1 | !!(data_byte & read_data_mask); >>>> + ncmds++; >>>> } >>>> >>>> /* >>>> @@ -2905,7 +2907,16 @@ static const u32 *spi_nor_get_map_in_use(struct spi_nor *nor, const u32 *smpt, >>>> * >>>> * Find the matching configuration map. >>>> */ >>>> - while (i < smpt_len) { >>>> + for (nmaps = 0; i < smpt_len; nmaps++) { >>>> + /* >>>> + * The map selector is limited to a maximum of 8 bits, allowing >>>> + * for a maximum of 256 possible map configurations. The total >>>> + * number of map configurations should be addressable by the >>>> + * total number of bits described by the detection commands. >>>> + */ >>>> + if (ncmds && nmaps >= (1 << (ncmds + 1))) >>>> + break; > > You're no longer checking that when ncmds == 0 nmaps has to be 1. So, > say the chip exposed no smpt commands and has several maps defined, > map_id will be 0 while it should have be "undefined". My version > would return an error, but yours tries to find map_id 0. yep, I missed the ncmds == 0 case. > >>>> + >>> >>> Maybe I missed something but it sounds like this change is just >>> optimizing the SPMT parsing a bit, and to be honest, I'm not sure this >>> is really needed. Most of the time, smpt_len will be rather small, so >>> trying to bail out earlier is not bringing much perf improvements. >> >> It's rather a smtp validity check. I want to return an error if there are not >> enough detection commands to identify the map id. > > You would have failed the same way without this validity check after a > maximum of smpt_len iterations, right? > Right. The correct fix would be to count nmaps in a loop, then do these checks, and if all ok, search for the map_id in another loop :). ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/