Hello Joacim,
On 01.11.21 11:07, Joacim Zetterling wrote:
> On Sat, Oct 30, 2021 at 03:45:57PM +0200, Ahmad Fatoum wrote:
>> On 29.10.21 13:06, Joacim Zetterling wrote:
>>> The imx8mn has a 16-bit SDRAM bus width access but the calculation
>>> of the memory size treat it as a 32-bit width bus which makes the
>>> memory calculation to be wrong (meminfo wrong and memtest fails).
>>>
>>> There is a difference between the imx7 and the imx8 familys.
>>> The imx8 family has a device config field in the master register of
>>> the DDRC controller which the imx7 family doesn't have (the bus width
>>> is 32-bit as default).
>>>
>>> The device config field together with the DQ configuration tells us
>>> the actual bus width of the device for a correct mem size calculaton.
>>>
>>> From the imx8mn reference manual:
>>> +----------------------------------------------------+
>>> | Field | Function |
>>> |----------------------------------------------------|
>>> | 31-30 | Indicates the configuration of the |
>>> | | device used in the system. |
>>> | device_config | 00b - x4 device |
>>> | | 01b - x8 device |
>>> | | 10b - x16 device |
>>> | | 11b - x32 device |
>>> +----------------------------------------------------+
>>> ...
>>> ...
>>>
>>> The imx8 supports a bus width of 4 bits or x4 (device_config b00).
>>> This is a problem for the calculation of the mem size when it only
>>> handle the bus width in bytes. Therefore we must treat the mem size
>>> calculation for the half bus width (width = 0) in a special way.
>>> Do the calculation with one byte width and then divide the mem size
>>> by 2 later on.
>>>
>>> Tested on the IMX8MN Evk with 2GB DDR4 and on a IMX8MN custom board
>>> with 2GB LPDDR4, checked size and made memory test. Both platforms
>>> has a mstr_device_config of b10 and the mstr_bus_width of b00.
>>>
>>> Signed-off-by: Joacim Zetterling <[email protected]>
>>
>> I agree that the computation for the nano is wrong. I have myself
>> a board with 1GB LPDDR4 here and with this patch now, it yields
>> a correct result.
>>
>> I checked against other boards we have in tree:
>>
>> arch/arm/boards/zii-imx8mq-dev/ddr_init.c
>> 45: reg32_write(0x3d400000,0xa3080020);
>>
>> arch/arm/boards/nxp-imx8mn-evk/ddr4-timing.c
>> 15: { 0x3d400000, 0x81040010 },
>>
>> arch/arm/boards/nxp-imx8mn-evk/lpddr4-timing.c
>> 19: {0x3d400000, 0xa3080020},
>>
>> arch/arm/boards/protonic-imx8m/lpddr4-timing-prt8mm.c
>> 16: { DDRC_MSTR(0), 0xa1080020 },
>>
>> arch/arm/boards/nxp-imx8mp-evk/lpddr4-timing.c
>> 14: { 0x3d400000, 0xa3080020 },
>>
>> arch/arm/boards/nxp-imx8mq-evk/ddr_init.c
>> 45: reg32_write(0x3d400000,0xa3080020);
>>
>> arch/arm/boards/phytec-som-imx8mq/ddr_init.c
>> 45: reg32_write(0x3d400000,0xa1080020);
>>
>> arch/arm/boards/nxp-imx8mm-evk/lpddr4-timing.c
>> 16: { DDRC_MSTR(0), 0xa1080020 },
>>
>> arch/arm/boards/mnt-reform/lpddr4-timing.c
>> 15: { DDRC_MSTR(0), 0xa0080020 | (LPDDR4_CS << 24) },
>>
>> And all of them have a width of x16. I find it hard to believe that all
>> of these boards have so far detected double the actual RAM.
>>
>> I am wondering if there is another parameter we are missing here.
>>
>> Cheers,
>> Ahmad
>>
>
> You are rigth!
>
> I started to dig into the imx8mn evk DDR4 board and found some things.
>
> The imx8mn DDR4 board has an other mem layout than rest of the boards
> compared agains my custom boaard or the LPDDR4 board, I see this.
>
> From the datasheets:
>
> DDR4 LPDDR4
> Banks 4 8
> Bank grps 2 1
> Rows 17 15
> Col 10 10
>
> Therefore we need to add two things:
>
> 1. We need the DDRC_ADDRMAP7_ROW_B16 and DDRC_ADDRMAP7_ROW_B17 support
> to support the DDR4 number of rows.
>
> 2. We need two add the DDRC_ADDRMAP8 and do a check for DDRC_ADDRMAP8_BG_B0
> DDRC_ADDRMAP8_BG_B1 to get the number of bank groups in the mem chip.
> i.e.
> ...
> #define DDRC_ADDRMAP8_BG_B1 GENMASK(13, 8)
> #define DDRC_ADDRMAP8_BG_B0 GENMASK( 4, 0)
> ...
> ...
> if (addrmap[8]) {
> if (FIELD_GET(DDRC_ADDRMAP8_BG_B0, addrmap[8]) != 0b11111)
> banks++;
> if (FIELD_GET(DDRC_ADDRMAP8_BG_B1, addrmap[8]) != 0b111111)
> banks++;
> }
> ...
> ...
>
> I verified this against our custom board (512MB) and the imx8 DDR4 evk board
> (2GiB)
> and seems ok. I also checked the values of the other boards in the repo
> and I think this will apply to them as well.
Great!
> What do You think! shall I make a v3 of this patch with the above changes?
Yes, please.
Cheers,
Ahmad
>
> Cheers,
> Joacim
>
>>> ---
>>> arch/arm/mach-imx/esdctl.c | 30 ++++++++++++++++++++++--------
>>> 1 file changed, 22 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/arch/arm/mach-imx/esdctl.c b/arch/arm/mach-imx/esdctl.c
>>> index e56da3cb76d4..1d76f26dfa39 100644
>>> --- a/arch/arm/mach-imx/esdctl.c
>>> +++ b/arch/arm/mach-imx/esdctl.c
>>> @@ -320,6 +320,7 @@ static int vf610_ddrmc_add_mem(void *mmdcbase, struct
>>> imx_esdctl_data *data)
>>> #define DDRC_MSTR_LPDDR4 BIT(5)
>>> #define DDRC_MSTR_DATA_BUS_WIDTH GENMASK(13, 12)
>>> #define DDRC_MSTR_ACTIVE_RANKS GENMASK(27, 24)
>>> +#define DDRC_MSTR_DEVICE_CONFIG GENMASK(31, 30)
>>>
>>> #define DDRC_ADDRMAP0_CS_BIT1 GENMASK(12, 8)
>>>
>>> @@ -361,7 +362,7 @@ static resource_size_t
>>> imx_ddrc_sdram_size(void __iomem *ddrc, const u32 addrmap[],
>>> u8 col_max, const u8 col_b[], unsigned int col_b_num,
>>> u8 row_max, const u8 row_b[], unsigned int row_b_num,
>>> - bool reduced_adress_space)
>>> + bool reduced_adress_space, bool is_imx8)
>>> {
>>> const u32 mstr = readl(ddrc + DDRC_MSTR);
>>> unsigned int banks, ranks, columns, rows, active_ranks, width;
>>> @@ -384,15 +385,20 @@ imx_ddrc_sdram_size(void __iomem *ddrc, const u32
>>> addrmap[],
>>> BUG();
>>> }
>>>
>>> + /* Bus width in bytes, 0 means half byte or 4-bit mode */
>>> + if (is_imx8)
>>> + width = (1 << FIELD_GET(DDRC_MSTR_DEVICE_CONFIG, mstr)) >> 1;
>>> + else
>>> + width = 4;
>>> +
>>> switch (FIELD_GET(DDRC_MSTR_DATA_BUS_WIDTH, mstr)) {
>>> case 0b00: /* Full DQ bus */
>>> - width = 4;
>>> break;
>>> - case 0b01: /* Half DQ bus */
>>> - width = 2;
>>> + case 0b01: /* Half DQ bus */
>>> + width >>= 1;
>>> break;
>>> case 0b10: /* Quarter DQ bus */
>>> - width = 1;
>>> + width >>= 2;
>>> break;
>>> default:
>>> BUG();
>>> @@ -412,7 +418,15 @@ imx_ddrc_sdram_size(void __iomem *ddrc, const u32
>>> addrmap[],
>>> columns = imx_ddrc_count_bits(col_max, col_b, col_b_num);
>>> rows = imx_ddrc_count_bits(row_max, row_b, row_b_num);
>>>
>>> - size = memory_sdram_size(columns, rows, 1 << banks, width) << ranks;
>>> + /*
>>> + * Special case when bus width is 0 or x4 mode,
>>> + * calculate the mem size and then divide the size by 2.
>>> + */
>>> + if (width)
>>> + size = memory_sdram_size(columns, rows, 1 << banks, width);
>>> + else
>>> + size = memory_sdram_size(columns, rows, 1 << banks, 1) >> 1;
>>> + size <<= ranks;
>>>
>>> return reduced_adress_space ? size * 3 / 4 : size;
>>> }
>>> @@ -466,7 +480,7 @@ static resource_size_t imx8m_ddrc_sdram_size(void
>>> __iomem *ddrc)
>>> return imx_ddrc_sdram_size(ddrc, addrmap,
>>> 12, ARRAY_AND_SIZE(col_b),
>>> 16, ARRAY_AND_SIZE(row_b),
>>> - reduced_adress_space);
>>> + reduced_adress_space, true);
>>> }
>>>
>>> static int imx8m_ddrc_add_mem(void *mmdcbase, struct imx_esdctl_data *data)
>>> @@ -508,7 +522,7 @@ static resource_size_t imx7d_ddrc_sdram_size(void
>>> __iomem *ddrc)
>>> return imx_ddrc_sdram_size(ddrc, addrmap,
>>> 11, ARRAY_AND_SIZE(col_b),
>>> 15, ARRAY_AND_SIZE(row_b),
>>> - reduced_adress_space);
>>> + reduced_adress_space, false);
>>> }
>>>
>>> static int imx7d_ddrc_add_mem(void *mmdcbase, struct imx_esdctl_data *data)
>>>
>>
>>
>> --
>> Pengutronix e.K. | |
>> Steuerwalder Str. 21 |
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>> |
>> 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
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>
--
Pengutronix e.K. | |
Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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