| Message ID | 20200722150113.1.Ia50ab5cb8a6d3a73d302e6bdc25542d48ffd27f4@changeid (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 0feea33d79825d05b5ede30947db4df34722b463 |
| Headers | show |
| Series | soc: qcom-geni-se: Don't use relaxed writes when writing commands | expand |
Quoting Douglas Anderson (2020-07-22 15:01:20) > Writing the command is the final step in kicking off a transfer. > Let's use writel() to ensure that any other memory accesses are done > before the command kicks off. It's expected that this is mostly > relevant if we're in DMA mode but since it doesn't appear to regress > performance in a measurable way [1] even in PIO mode and it's easier > to reason about then let's just always use it. > > NOTE: this patch came about due to code inspection. No actual > problems were observed that this patch fixes. > > [1] Tested by timing "flashrom -p ec" on a Chromebook which stresses > GENI SPI a lot. > > Suggested-by: Stephen Boyd <swboyd@chromium.org> > Signed-off-by: Douglas Anderson <dianders@chromium.org> > --- Reviewed-by: Stephen Boyd <swboyd@chromium.org>
On 7/23/2020 3:31 AM, Douglas Anderson wrote: > Writing the command is the final step in kicking off a transfer. > Let's use writel() to ensure that any other memory accesses are done > before the command kicks off. It's expected that this is mostly > relevant if we're in DMA mode but since it doesn't appear to regress > performance in a measurable way [1] even in PIO mode and it's easier > to reason about then let's just always use it. > > NOTE: this patch came about due to code inspection. No actual > problems were observed that this patch fixes. > > [1] Tested by timing "flashrom -p ec" on a Chromebook which stresses > GENI SPI a lot. > > Suggested-by: Stephen Boyd <swboyd@chromium.org> > Signed-off-by: Douglas Anderson <dianders@chromium.org> > --- Reviewed-by: Akash Asthana <akashast@codeaurora.org>
On 7/23/2020 3:31 AM, Douglas Anderson wrote: > Writing the command is the final step in kicking off a transfer. > Let's use writel() to ensure that any other memory accesses are done > before the command kicks off. It's expected that this is mostly > relevant if we're in DMA mode but since it doesn't appear to regress > performance in a measurable way [1] even in PIO mode and it's easier > to reason about then let's just always use it. > > NOTE: this patch came about due to code inspection. No actual > problems were observed that this patch fixes. > > [1] Tested by timing "flashrom -p ec" on a Chromebook which stresses > GENI SPI a lot. > > Suggested-by: Stephen Boyd <swboyd@chromium.org> > Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Mukesh Kumar Savaliya <msavaliy@codeaurora.org> > --- > > include/linux/qcom-geni-se.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/include/linux/qcom-geni-se.h b/include/linux/qcom-geni-se.h > index dd464943f717..f50c73be1428 100644 > --- a/include/linux/qcom-geni-se.h > +++ b/include/linux/qcom-geni-se.h > @@ -262,7 +262,7 @@ static inline void geni_se_setup_m_cmd(struct geni_se *se, u32 cmd, u32 params) > u32 m_cmd; > > m_cmd = (cmd << M_OPCODE_SHFT) | (params & M_PARAMS_MSK); > - writel_relaxed(m_cmd, se->base + SE_GENI_M_CMD0); > + writel(m_cmd, se->base + SE_GENI_M_CMD0); > } > > /** > @@ -282,7 +282,7 @@ static inline void geni_se_setup_s_cmd(struct geni_se *se, u32 cmd, u32 params) > s_cmd &= ~(S_OPCODE_MSK | S_PARAMS_MSK); > s_cmd |= (cmd << S_OPCODE_SHFT); > s_cmd |= (params & S_PARAMS_MSK); > - writel_relaxed(s_cmd, se->base + SE_GENI_S_CMD0); > + writel(s_cmd, se->base + SE_GENI_S_CMD0); > } > > /**
diff --git a/include/linux/qcom-geni-se.h b/include/linux/qcom-geni-se.h index dd464943f717..f50c73be1428 100644 --- a/include/linux/qcom-geni-se.h +++ b/include/linux/qcom-geni-se.h @@ -262,7 +262,7 @@ static inline void geni_se_setup_m_cmd(struct geni_se *se, u32 cmd, u32 params) u32 m_cmd; m_cmd = (cmd << M_OPCODE_SHFT) | (params & M_PARAMS_MSK); - writel_relaxed(m_cmd, se->base + SE_GENI_M_CMD0); + writel(m_cmd, se->base + SE_GENI_M_CMD0); } /** @@ -282,7 +282,7 @@ static inline void geni_se_setup_s_cmd(struct geni_se *se, u32 cmd, u32 params) s_cmd &= ~(S_OPCODE_MSK | S_PARAMS_MSK); s_cmd |= (cmd << S_OPCODE_SHFT); s_cmd |= (params & S_PARAMS_MSK); - writel_relaxed(s_cmd, se->base + SE_GENI_S_CMD0); + writel(s_cmd, se->base + SE_GENI_S_CMD0); } /**
Writing the command is the final step in kicking off a transfer. Let's use writel() to ensure that any other memory accesses are done before the command kicks off. It's expected that this is mostly relevant if we're in DMA mode but since it doesn't appear to regress performance in a measurable way [1] even in PIO mode and it's easier to reason about then let's just always use it. NOTE: this patch came about due to code inspection. No actual problems were observed that this patch fixes. [1] Tested by timing "flashrom -p ec" on a Chromebook which stresses GENI SPI a lot. Suggested-by: Stephen Boyd <swboyd@chromium.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> --- include/linux/qcom-geni-se.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)