From: Martin Blumenstingl <martin.blumenstingl@googlemail.com> To: linux-amlogic@lists.infradead.org, jbrunet@baylibre.com, narmstrong@baylibre.com Cc: linux-clk@vger.kernel.org, carlo@caione.org, Martin Blumenstingl <martin.blumenstingl@googlemail.com> Subject: [PATCH 0/2] Meson8b: fixes for the cpu_scale_div clock Date: Thu, 27 Sep 2018 10:59:19 +0200 [thread overview] Message-ID: <20180927085921.24627-1-martin.blumenstingl@googlemail.com> (raw) While trying to add support for the TWD timer I found that our CPU clock calculation (when running off the "cpu_scale_div clock) is incorrect. The main problem was the cpu_scale_div clock: it's divider table has an off-by-one error. the old formula was: parent_rate / 2 * register_value however, testing shows that the correct formula is: parent_rate / 2 * (register value + 1) See the commit message of patch #1 for a complete description of the problem and it's history. While looking at the "cpu_scale_div" clock I also found that it's register width was also off-by-one, so this is fixed in a separate patch as well. Both patches are not critical because I haven't seen a case where u-boot uses cpu_scale_div for the CPU clock. It's only a problem when playing with the CPU clock in u-boot (by writing registers manually) or as soon as we support CPU frequency scaling. Martin Blumenstingl (2): clk: meson: meson8b: fix incorrect divider mapping in cpu_scale_table clk: meson: meson8b: fix the width of the cpu_scale_div clock drivers/clk/meson/meson8b.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) -- 2.19.0
WARNING: multiple messages have this Message-ID (diff)
From: martin.blumenstingl@googlemail.com (Martin Blumenstingl) To: linus-amlogic@lists.infradead.org Subject: [PATCH 0/2] Meson8b: fixes for the cpu_scale_div clock Date: Thu, 27 Sep 2018 10:59:19 +0200 [thread overview] Message-ID: <20180927085921.24627-1-martin.blumenstingl@googlemail.com> (raw) While trying to add support for the TWD timer I found that our CPU clock calculation (when running off the "cpu_scale_div clock) is incorrect. The main problem was the cpu_scale_div clock: it's divider table has an off-by-one error. the old formula was: parent_rate / 2 * register_value however, testing shows that the correct formula is: parent_rate / 2 * (register value + 1) See the commit message of patch #1 for a complete description of the problem and it's history. While looking at the "cpu_scale_div" clock I also found that it's register width was also off-by-one, so this is fixed in a separate patch as well. Both patches are not critical because I haven't seen a case where u-boot uses cpu_scale_div for the CPU clock. It's only a problem when playing with the CPU clock in u-boot (by writing registers manually) or as soon as we support CPU frequency scaling. Martin Blumenstingl (2): clk: meson: meson8b: fix incorrect divider mapping in cpu_scale_table clk: meson: meson8b: fix the width of the cpu_scale_div clock drivers/clk/meson/meson8b.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) -- 2.19.0
next reply other threads:[~2018-09-27 15:16 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-09-27 8:59 Martin Blumenstingl [this message] 2018-09-27 8:59 ` [PATCH 0/2] Meson8b: fixes for the cpu_scale_div clock Martin Blumenstingl 2018-09-27 8:59 ` [PATCH 1/2] clk: meson: meson8b: fix incorrect divider mapping in cpu_scale_table Martin Blumenstingl 2018-09-27 8:59 ` Martin Blumenstingl 2018-09-27 8:59 ` [PATCH 2/2] clk: meson: meson8b: fix the width of the cpu_scale_div clock Martin Blumenstingl 2018-09-27 8:59 ` Martin Blumenstingl 2018-11-08 14:16 ` [PATCH 0/2] Meson8b: fixes for " Neil Armstrong 2018-11-08 14:16 ` Neil Armstrong 2018-11-16 8:30 ` Neil Armstrong 2018-11-16 8:30 ` Neil Armstrong
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=20180927085921.24627-1-martin.blumenstingl@googlemail.com \ --to=martin.blumenstingl@googlemail.com \ --cc=carlo@caione.org \ --cc=jbrunet@baylibre.com \ --cc=linux-amlogic@lists.infradead.org \ --cc=linux-clk@vger.kernel.org \ --cc=narmstrong@baylibre.com \ /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: linkBe 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.