From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.16]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5CE3127442; Tue, 17 Sep 2024 13:58:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726581523; cv=none; b=NF73c/EOKy1+m6DPGp0LdQ8bs4ALMDAotqFXYQxCcksoHkz0OJiYtHXPzFBxqdWWjLZpX8HAh480aUZNNHI4sz1JwhTOdwfNTWZ+O2IbZqIOci3Uu7wUgUeywV0zX4+FP40jRNCCcwNpcq16FjBd+aRol/tE+1UflhTtoCVFvWM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726581523; c=relaxed/simple; bh=ZXeO3cCGpQp8km56A8jsnfTWizOI32RKsbTpSpPVZrM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WZCeeLZ1U50V6MaBgfo98JYEeTz3Tz4BJSgEUqcdMalBD8U6VEW3VZ3BUnfNLioNH66Go3JY750fAvkRuckv0kTZ11h5V+Av4wU2AE0if7IcC1rh0Qrpw5kqXGKJbalu00Ygvj/VTK0g0hLyAJfkDuW+QN7ZfYhxg2vVDcYTCbI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=R8hfm7Sh; arc=none smtp.client-ip=198.175.65.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="R8hfm7Sh" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1726581522; x=1758117522; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=ZXeO3cCGpQp8km56A8jsnfTWizOI32RKsbTpSpPVZrM=; b=R8hfm7Shu6Ljm6DAPZ1w28kyBuHWeDcMac43GudnbDDH6u8GOA+WUgT1 +gnf3UWTq0oEfAKob4AHtLCM879fbiydvALkEzgf5c6uRtXSEQ5CRxQQg 8HXEZkDi0iJ8RkeT5NWQH03x1UmhXqROkTbAWUYPydTSqmZvG0fvPpFou kJqYgkbYZs//2gvWD+dh/WVwb/hnerLDsnxCRWXYlH0uTGl8ujZwyp6tE F4lV3IbM/aemYSuYc9kJJPtOnGQyzDmha7YzKR4teDa26sus2kp7HUP+b dVh6XmgKvmKWSunHnYZqI7UGDBAxan/lYGQqF4FapinpPL6R/MAUdIcN2 Q==; X-CSE-ConnectionGUID: oORtztbiTcy7u2kxEzWo4g== X-CSE-MsgGUID: 8/HOxCK/RPuYxAyW4chHNA== X-IronPort-AV: E=McAfee;i="6700,10204,11198"; a="25538897" X-IronPort-AV: E=Sophos;i="6.10,235,1719903600"; d="scan'208";a="25538897" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Sep 2024 06:58:41 -0700 X-CSE-ConnectionGUID: DrsjfDWiQXS1CygqQkRpgQ== X-CSE-MsgGUID: +42bj6NxTM6E86iNmlIkXg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.10,235,1719903600"; d="scan'208";a="100036764" Received: from smile.fi.intel.com ([10.237.72.54]) by fmviesa001.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Sep 2024 06:58:38 -0700 Received: from andy by smile.fi.intel.com with local (Exim 4.98) (envelope-from ) id 1sqYix-00000009q6z-1l1f; Tue, 17 Sep 2024 16:58:35 +0300 Date: Tue, 17 Sep 2024 16:58:35 +0300 From: Andy Shevchenko To: Palmer Dabbelt Cc: Sunil V L , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, linux-riscv@lists.infradead.org, Greg KH , jirislaby@kernel.org, andrei.warkentin@intel.com, apatel@ventanamicro.com, ajones@ventanamicro.com, dfustini@tenstorrent.com Subject: Re: [PATCH] serial: 8250_platform: Enable generic 16550A platform devices Message-ID: References: <20240730051218.767580-1-sunilvl@ventanamicro.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo On Tue, Sep 17, 2024 at 06:10:25AM -0700, Palmer Dabbelt wrote: > On Mon, 29 Jul 2024 22:12:18 PDT (-0700), Sunil V L wrote: > > Currently, 8250_platform driver is used only for devices with fixed > > serial ports (plat_serial8250_port). Extend this driver for any generic > > 16550A platform devices which can be probed using standard hardware > > discovery mechanisms like ACPI. > > > > This is required in particular for RISC-V which has non-PNP generic > > 16550A compatible UART that needs to be enumerated as ACPI platform > > device. > It seems a bit awkward that we need something RISC-V specific here. I > guess the idea is that we don't want to depend on PNP because we'd end > up with a bunch of PCI dependencies as well? That seems like kind of an > odd way to do things, but I'm frequently suprised by ACPI stuff so We have the same for HSUART on Intel (see 8250_dw.c). The ACPI devices use different approach than PNP. PNP has the exact requirements for compatibility with the legacy UARTs (to some extend). It puts some limitations. I believe having specifics for RISC-V is fine. But I haven't checked the real IP used in the SoC. If it's one that we have the existing driver for (like again mentioned 8250_dw.c), then it should be added there. TL;DR: so, what is the IP is in hardware for UART? Custom? -- With Best Regards, Andy Shevchenko