On 03/02/2025 18:42, Dmitry Baryshkov wrote:
> On Mon, Feb 03, 2025 at 06:29:18PM +0100, Krzysztof Kozlowski wrote:
>> PHY_CMN_CLK_CFG0 register is updated by the PHY driver and by two
>> divider clocks from Common Clock Framework:
>> devm_clk_hw_register_divider_parent_hw(). Concurrent access by the
>> clocks side is protected with spinlock, however driver's side in
>> restoring state is not. Restoring state is called from
>> msm_dsi_phy_enable(), so there could be a path leading to concurrent and
>> conflicting updates with clock framework.
>>
>> Add missing lock usage on the PHY driver side, encapsulated in its own
>> function so the code will be still readable.
>>
>> Fixes: 1ef7c99d145c ("drm/msm/dsi: add support for 7nm DSI PHY/PLL")
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
>> ---
>> drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c | 13 +++++++++++--
>> 1 file changed, 11 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c
>> index 031446c87daec0af3f81df324158311f5a80014e..c164f845653816291ad96c863257f75462ef58e7 100644
>> --- a/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c
>> +++ b/drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c
>> @@ -372,6 +372,15 @@ static void dsi_pll_enable_pll_bias(struct dsi_pll_7nm *pll)
>> ndelay(250);
>> }
>>
>> +static void dsi_pll_cmn_clk_cfg0_write(struct dsi_pll_7nm *pll, u32 val)
>> +{
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&pll->postdiv_lock, flags);
>> + writel(val, pll->phy->base + REG_DSI_7nm_PHY_CMN_CLK_CFG0);
>> + spin_unlock_irqrestore(&pll->postdiv_lock, flags);
>> +}
>> +
>> static void dsi_pll_disable_global_clk(struct dsi_pll_7nm *pll)
>> {
>> u32 data;
>> @@ -574,8 +583,8 @@ static int dsi_7nm_pll_restore_state(struct msm_dsi_phy *phy)
>> val |= cached->pll_out_div;
>> writel(val, pll_7nm->phy->pll_base + REG_DSI_7nm_PHY_PLL_PLL_OUTDIV_RATE);
>>
>> - writel(cached->bit_clk_div | (cached->pix_clk_div << 4),
>> - phy_base + REG_DSI_7nm_PHY_CMN_CLK_CFG0);
>> + dsi_pll_cmn_clk_cfg0_write(pll_7nm,
>> + cached->bit_clk_div | (cached->pix_clk_div << 4));
>
> Ideally this would be FIELD_PREP or a special function generated for you
> in the header.
There is no header. That's patch #1 and I do not see how changing this
to FIELDPREP is anyhow related to the actual problem being solved here.
Best regards,
Krzysztof
