linux-kernel - [RFC PATCH] phy: dphy: Fix Unit Interval(UI) calculation formula

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <20241031123643.272111-1-changhuang.liang@starfivetech.com>
Date: Thu, 31 Oct 2024 05:36:43 -0700
From: Changhuang Liang <changhuang.liang@...rfivetech.com>
To: Vinod Koul <vkoul@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Maxime Ripard <mripard@...nel.org>
Cc: Changhuang Liang <changhuang.liang@...rfivetech.com>,
	linux-phy@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH] phy: dphy: Fix Unit Interval(UI) calculation formula

ALIGN() expects its second argument to be a power of 2, but in the
context, the hs_clk_rate will not satisfy this condition in most
cases. This may lead to unknown results in the UI calculation.

So, let fix the UI calculation formula.

Fixes: dddc97e82303 ("phy: dphy: Add configuration helpers")
Signed-off-by: Changhuang Liang <changhuang.liang@...rfivetech.com>
---

Hi, Maxime

This patch may require your careful review. I have no environmental test
so there is no guarantee of any effect.

This UI calculation is a reference to your patch:
https://lore.kernel.org/all/aa491b814100a670ad16b646765005efbdae05d9.1536138624.git-series.maxime.ripard@bootlin.com/

Best Regards,
Changhuang

 drivers/phy/phy-core-mipi-dphy.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/phy/phy-core-mipi-dphy.c b/drivers/phy/phy-core-mipi-dphy.c
index f4956a417a47..c7712e594dbf 100644
--- a/drivers/phy/phy-core-mipi-dphy.c
+++ b/drivers/phy/phy-core-mipi-dphy.c
@@ -33,8 +33,7 @@ static int phy_mipi_dphy_calc_config(unsigned long pixel_clock,
 		do_div(hs_clk_rate, lanes);
 	}

-	ui = ALIGN(PSEC_PER_SEC, hs_clk_rate);
-	do_div(ui, hs_clk_rate);
+	ui = DIV_ROUND_UP(PSEC_PER_SEC, hs_clk_rate);

 	cfg->clk_miss = 0;
 	cfg->clk_post = 60000 + 52 * ui;
@@ -111,8 +110,7 @@ int phy_mipi_dphy_config_validate(struct phy_configure_opts_mipi_dphy *cfg)
 	if (!cfg)
 		return -EINVAL;

-	ui = ALIGN(PSEC_PER_SEC, cfg->hs_clk_rate);
-	do_div(ui, cfg->hs_clk_rate);
+	ui = DIV_ROUND_UP(PSEC_PER_SEC, cfg->hs_clk_rate);

 	if (cfg->clk_miss > 60000)
 		return -EINVAL;
--
2.25.1