From: Peng Fan <peng.fan@nxp.com>
To: Ahmad Fatoum <a.fatoum@pengutronix.de>,
"Peng Fan (OSS)" <peng.fan@oss.nxp.com>
Cc: U-Boot Mailing List <u-boot@lists.denx.de>,
"barebox@lists.infradead.org" <barebox@lists.infradead.org>,
dl-uboot-imx <uboot-imx@nxp.com>,
Steffen Trumtrar <str@pengutronix.de>
Subject: RE: i.MX8/9: question about unused DDR PHY trained CSR board array
Date: Mon, 30 Sep 2024 06:38:45 +0000 [thread overview]
Message-ID: <PAXPR04MB8459A8BB89FAB50D6871EA9388762@PAXPR04MB8459.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <8074530f-720b-4aea-934b-c0643c356617@pengutronix.de>
Hi Ahmad,
> Subject: i.MX8/9: question about unused DDR PHY trained CSR board
> array
>
> Hello Peng,
>
> Looking at the DDR setup code for i.MX8M and i.MX9 that you had
> contributed, I am wondering about struct
> dram_cfg_param::ddrphy_trained_csr and the global
> ddrphy_trained_csr array.
>
> struct dram_cfg_param::ddrphy_trained_csr is presumably generated
> by the i.MX DDR tool and it seems populated by all the i.MX8M/9
> boards in U-Boot.
>
> This struct member is wholly unused though and instead a global
> ddrphy_trained_csr is used.
>
> What I wonder about is whether it's possible for the DDR tool to
> generate a different ddrphy_trained_csr than the default:
>
> 1) If yes, we should drop the global ddrphy_trained_csr and actually
> use
> the board-specific array
>
> 2) If not, we should drop the board-specific array and perhaps ask for
> the DDR tool to be changed
>
> I initially assumed 1) and because all boards supported by barebox had
> a board-specific ddrphy_trained_csr that's identical to the global
> ddrphy_trained_csr, I dropped the unused array[1][2].
>
> I now have the DDR settings for an i.MX9 LPDDR4 board in front of me
> that has different contents for struct
> dram_cfg_param::ddrphy_trained_csr than the default.
>
> I will inquire how that came about, but in parallel I wanted to ask you if
> this is supposed to happen and to alert you to this issue.
Thanks for raising this issue. I think board specific csr should be used.
I will check with DDR TOOL owners on this.
>
> The way things are, this is either a bug or a missed space saving
> opportunity for U-Boot.
Thanks,
Peng.
prev parent reply other threads:[~2024-09-30 6:39 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-27 14:08 Ahmad Fatoum
2024-09-30 6:38 ` Peng Fan [this message]
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