All of lore.kernel.org
 help / color / mirror / Atom feed
From: Paul Cercueil <paul@crapouillou.net>
To: Michael Turquette <mturquette@baylibre.com>,
	Stephen Boyd <sboyd@kernel.org>
Cc: od@zcrc.me, linux-clk@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Paul Cercueil <paul@crapouillou.net>,
	stable@vger.kernel.org
Subject: [PATCH] clk: ingenic: Fix divider calculation with div tables
Date: Sat, 12 Dec 2020 13:57:33 +0000	[thread overview]
Message-ID: <20201212135733.38050-1-paul@crapouillou.net> (raw)

The previous code assumed that a higher hardware value always resulted
in a bigger divider, which is correct for the regular clocks, but is
an invalid assumption when a divider table is provided for the clock.

Perfect example of this is the PLL0_HALF clock, which applies a /2
divider with the hardware value 0, and a /1 divider otherwise.

Fixes: a9fa2893fcc6 ("clk: ingenic: Add support for divider tables")
Cc: <stable@vger.kernel.org> # 5.2
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/clk/ingenic/cgu.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/ingenic/cgu.c b/drivers/clk/ingenic/cgu.c
index dac6edc670cc..c8e9cb6c8e39 100644
--- a/drivers/clk/ingenic/cgu.c
+++ b/drivers/clk/ingenic/cgu.c
@@ -392,15 +392,21 @@ static unsigned int
 ingenic_clk_calc_hw_div(const struct ingenic_cgu_clk_info *clk_info,
 			unsigned int div)
 {
-	unsigned int i;
+	unsigned int i, best_i = 0, best = (unsigned int)-1;
 
 	for (i = 0; i < (1 << clk_info->div.bits)
 				&& clk_info->div.div_table[i]; i++) {
-		if (clk_info->div.div_table[i] >= div)
-			return i;
+		if (clk_info->div.div_table[i] >= div &&
+		    clk_info->div.div_table[i] < best) {
+			best = clk_info->div.div_table[i];
+			best_i = i;
+
+			if (div == best)
+				break;
+		}
 	}
 
-	return i - 1;
+	return best_i;
 }
 
 static unsigned
-- 
2.29.2


             reply	other threads:[~2020-12-12 13:58 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-12 13:57 Paul Cercueil [this message]
2020-12-20  0:05 ` [PATCH] clk: ingenic: Fix divider calculation with div tables Stephen Boyd

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201212135733.38050-1-paul@crapouillou.net \
    --to=paul@crapouillou.net \
    --cc=linux-clk@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mturquette@baylibre.com \
    --cc=od@zcrc.me \
    --cc=sboyd@kernel.org \
    --cc=stable@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.