[U-Boot] [PATCH 2/2] mv_ddr: ddr3: only use active chip-selects when tuning ODT

[Baruch Siach]

Hi Chris,

On Thu, Feb 28 2019, Chris Packham wrote:
> From: Chris Packham <chris.packham at alliedtelesis.co.nz>
>
> Inactive chip-selects will give invalid values for read_sample so don't
> consider them when trying to determine the overall min/max read sample.
>
> Signed-off-by: Chris Packham <chris.packham at alliedtelesis.co.nz>
>
> [https://github.com/MarvellEmbeddedProcessors/mv-ddr-marvell/pull/18]
> Signed-off-by: Chris Packham <judge.packham at gmail.com>
> ---
> Hi Baruch,
>
> Does this help with your boards? It's not the custom g_odt_config you
> were after but it might mean that the code gets the right ODT value so
> you don't have to override it.

Maybe. The code looks pretty opaque to me.

Ideally we would like to have ODT_CONFIG (offset 0x1494) set to 0x30000
for all Clearfog platforms, since only ODT0 is connected. This value is
good for both 1CS and 2CS systems, although the current 0x10000 is also
fine for 1CS.

The current 2CS default hard-coded value of 0x120012 is good when both
ODT0/ODT1 are connected and both chip-selects are used. 0x30000 is not
optimal for these systems.

baruch

>  drivers/ddr/marvell/a38x/ddr3_training_hw_algo.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/ddr/marvell/a38x/ddr3_training_hw_algo.c b/drivers/ddr/marvell/a38x/ddr3_training_hw_algo.c
> index db0f8ad7fb55..df832ac6dce0 100644
> --- a/drivers/ddr/marvell/a38x/ddr3_training_hw_algo.c
> +++ b/drivers/ddr/marvell/a38x/ddr3_training_hw_algo.c
> @@ -50,6 +50,7 @@ int ddr3_tip_write_additional_odt_setting(u32 dev_num, u32 if_id)
>  	int max_phase = MIN_VALUE, current_phase;
>  	enum hws_access_type access_type = ACCESS_TYPE_UNICAST;
>  	u32 octets_per_if_num = ddr3_tip_dev_attr_get(dev_num, MV_ATTR_OCTET_PER_INTERFACE);
> +	unsigned int max_cs = mv_ddr_cs_num_get();
>
>  	CHECK_STATUS(ddr3_tip_if_write(dev_num, access_type, if_id,
>  				       DUNIT_ODT_CTRL_REG,
> @@ -59,7 +60,7 @@ int ddr3_tip_write_additional_odt_setting(u32 dev_num, u32 if_id)
>  				      data_read, MASK_ALL_BITS));
>  	val = data_read[if_id];
>
> -	for (cs_num = 0; cs_num < MAX_CS_NUM; cs_num++) {
> +	for (cs_num = 0; cs_num < max_cs; cs_num++) {
>  		read_sample[cs_num] = GET_RD_SAMPLE_DELAY(val, cs_num);
>
>  		/* find maximum of read_samples */


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